Add "---dbus---" sections to the NMSetting property docs, in the same
style as the plugin docs, parse them out into a file
"nm-setting-docs-overrides.xml", and use them to override the GObject
property docs in nm-setting-docs.xml.

This lets us put more D-Bus-specific information in the setting docs,
without cluttering up the property docs, and it also lets us document
dbus-only properties.

Move the settings/plugins doc generation from libnm-util to
libnm-core, since libnm-util isn't being updated for all new
properties.

With this commit, the keyfile and ifcfg-rh documentation is basically
unchanged, except that deprecated properties are now gone, and new
properties have been added, and the sections are in a different order.
(generate-plugin-docs.pl just outputs the settings in Makefile order,
and they were unsorted in libnm-util, but are sorted in libnm-core).

The settings documentation used for nm-settings.5, the D-Bus API docs,
and the nmcli help is changed a bit more at this point, and mostly for
the worse, since the libnm-core setting properties don't match up with
the D-Bus API as well as the libnm-util ones do. To be fixed...

(I also removed the "plugins docs" line in each plugin docs comment
block while moving them, since those blocks will be used for more than
just plugins soon, and it's sort of obvious anyway.)

Libraries need to include <gi18n-lib.h>, not <gi18n.h>, so that _()
will get defined to "dgettext (GETTEXT_DOMAIN, string)" rather than
"gettext (string)" (which will use the program's default domain, which
works fine for programs in the NetworkManager tree, but not for
external users). Likewise, we need to call bindtextdomain() so that
gettext can find the translations if the library is installed in a
different prefix from the program using it (and
bind_textdomain_codeset(), so it will know the translations are in
UTF-8 even if the locale isn't).

(The fact that no one noticed this was broken before is because the
libraries didn't really start returning useful translated strings much
until 0.9.10, and none of the out-of-tree clients have been updated to
actually show those strings to users yet.)

config.h should be included from every .c file, and it should be
included before any other include. Fix that.

(As a side effect of how I did this, this also changes us to
consistently use "config.h" rather than <config.h>. To the extent that
it matters [which is not much], quotes are more correct anyway, since
we're talking about a file in our own build tree, not a system
include.)

nm_setting_verify() took a GSList of other NMSettings, but really it
would just be simpler all around to pass the NMConnection instead...

This means that several formerly NMSetting-branded functions that
operated on lists-of-settings now get replaced with
NMConnection-branded functions instead.

Each setting type was defining its own error type, but most of them
had exactly the same three errors ("unknown", "missing property", and
"invalid property"), and none of the other values was of much use
programmatically anyway.

So, this commit merges NMSettingError, NMSettingAdslError, etc, all
into NMConnectionError. (The reason for merging into NMConnectionError
rather than NMSettingError is that we also already have
"NMSettingsError", for errors related to the settings service, so
"NMConnectionError" is a less-confusable name for settings/connection
errors than "NMSettingError".)

Also, make sure that all of the affected error messages are localized,
and (where appropriate) prefix them with the relevant property name.

Renamed error codes:

NM_SETTING_ERROR_PROPERTY_NOT_FOUND -> NM_CONNECTION_ERROR_PROPERTY_NOT_FOUND
NM_SETTING_ERROR_PROPERTY_NOT_SECRET -> NM_CONNECTION_ERROR_PROPERTY_NOT_SECRET

Remapped error codes:

NM_SETTING_*_ERROR_MISSING_PROPERTY -> NM_CONNECTION_ERROR_MISSING_PROPERTY
NM_SETTING_*_ERROR_INVALID_PROPERTY -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_ERROR_PROPERTY_TYPE_MISMATCH -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_BLUETOOTH_ERROR_TYPE_SETTING_NOT_FOUND -> NM_CONNECTION_ERROR_INVALID_SETTING
NM_SETTING_BOND_ERROR_INVALID_OPTION -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_BOND_ERROR_MISSING_OPTION -> NM_CONNECTION_ERROR_MISSING_PROPERTY
NM_SETTING_CONNECTION_ERROR_TYPE_SETTING_NOT_FOUND -> NM_CONNECTION_ERROR_MISSING_SETTING
NM_SETTING_CONNECTION_ERROR_SLAVE_SETTING_NOT_FOUND -> NM_CONNECTION_ERROR_MISSING_SETTING
NM_SETTING_IP4_CONFIG_ERROR_NOT_ALLOWED_FOR_METHOD -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_IP6_CONFIG_ERROR_NOT_ALLOWED_FOR_METHOD -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_VLAN_ERROR_INVALID_PARENT -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_WIRELESS_SECURITY_ERROR_MISSING_802_1X_SETTING -> NM_CONNECTION_ERROR_MISSING_SETTING
NM_SETTING_WIRELESS_SECURITY_ERROR_LEAP_REQUIRES_802_1X -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_WIRELESS_SECURITY_ERROR_LEAP_REQUIRES_USERNAME -> NM_CONNECTION_ERROR_MISSING_PROPERTY
NM_SETTING_WIRELESS_SECURITY_ERROR_SHARED_KEY_REQUIRES_WEP -> NM_CONNECTION_ERROR_INVALID_PROPERTY
NM_SETTING_WIRELESS_ERROR_CHANNEL_REQUIRES_BAND -> NM_CONNECTION_ERROR_MISSING_PROPERTY

Dropped error codes (were previously defined but unused):

NM_SETTING_CDMA_ERROR_MISSING_SERIAL_SETTING
NM_SETTING_CONNECTION_ERROR_IP_CONFIG_NOT_ALLOWED
NM_SETTING_GSM_ERROR_MISSING_SERIAL_SETTING
NM_SETTING_PPP_ERROR_REQUIRE_MPPE_NOT_ALLOWED
NM_SETTING_PPPOE_ERROR_MISSING_PPP_SETTING
NM_SETTING_SERIAL_ERROR_MISSING_PPP_SETTING
NM_SETTING_WIRELESS_ERROR_MISSING_SECURITY_SETTING

In preparation for porting to GDBus, make nm_connection_to_dbus(),
etc, represent connections as GVariants of type 'a{sa{sv}}' rather
than as GHashTables-of-GHashTables-of-GValues.

This means we're constantly converting back and forth internally, but
this is just a stepping stone on the way to the full GDBus port, and
all of that code will go away again later.

It needs to be possible to deserialize a connection hash into an
invalid NMConnection; in particular, AddAndActivateConnection()
explicitly allows this.

Previously, the SetFunc and NotSetFunc passed to
_nm_setting_class_override_property() could return a verification
error immediately, but this functionality has to go away if we're
going to be able to deserialize invalid connections.

That functionality was only used in the handling of invalid virtual
interface names; reorganize how that code works so that
NMSettingConnection does all of the verification itself. (The code to
make sure that it returned the "correct" error domain in that case
turned out to be irrelevant, since the setting error domains don't get
serialized over D-Bus correctly anyway.)

NMParamSpecSpecialized existed basically to provide a version of
GParamSpecBoxed that could compare dbus-glib-valued properties
correctly.

However, g_param_values_cmp() was only used by NM directly in one
place (NMSetting's compare_property()), and we don't actually need to
indirect through GParamSpec there; we could just call
NMParamSpecSpecialized's value-comparison function directly.

So, change all NMParamSpecSpecialized properties to GParamSpecBoxed,
rename the _gvalues_compare() function it used to
"nm_property_compare()", and use that from NMSetting.

(g_param_values_cmp() also gets used internally by
g_param_value_defaults(), but all NMParamSpecSpecialized properties
have a default value of NULL, so GParamSpecBoxed's pointer-equality
check will do the job just fine there.)

Remove the virtual :interface-name properties and their getters, and
use property overrides to do backward-compat handling when
serializing/deserializing.

Now when constructing an NMConnection from a hash, if the virtual
property is set and the NMSettingConnection property isn't, then the
override for NMSettingConnection:interface-name will set that property
to the value of the virtual interface-name. And when converting an
NMConnection to a hash, the overrides for the virtual properties will
return the value of NMSettingConnection:interface-name.