Signed-off-by: Thomas Haller <thaller@redhat.com>

Signed-off-by: Thomas Haller <thaller@redhat.com>

The fact that NMRemoteConnection has to be an NMConnection and
therefore can't be an NMObject means that it needs to reimplement bits
of NMObject functionality (and likewise NMObject needs some special
magic to deal with it). Likewise, we will need a daemon-side
equivalent of NMObject as part of the gdbus port, and we would want
NMSettingsConnection to be able to inherit from this as well.

Solve this problem by making NMConnection into an interface, and
having NMRemoteConnection and NMSettingsConnection implement it. (We
use some hacks to keep the GHashTable of NMSettings objects inside
nm-connection.c rather than having to be implemented by the
implementations.)

Since NMConnection is no longer an instantiable type, this adds
NMSimpleConnection to replace the various non-D-Bus-based uses of
NMConnection throughout the code. nm_connection_new() becomes
nm_simple_connection_new(), nm_connection_new_from_hash() becomes
nm_simple_connection_new_from_hash(), and nm_connection_duplicate()
becomes nm_simple_connection_new_clone().

Previously, src/nm-ip4-config.h, libnm/nm-ip4-config.h, and
libnm-glib/nm-ip4-config.h all used "NM_IP4_CONFIG_H" as an include
guard, which meant that nm-test-utils.h could not tell which of them
was being included (and so, eg, if you tried to include
nm-ip4-config.h in a libnm test, it would fail to compile because
nm-test-utils.h was referring to symbols in src/nm-ip4-config.h).

Fix this by changing the include guards in the non-API-stable parts of
the tree:

  - libnm-glib/nm-ip4-config.h remains   NM_IP4_CONFIG_H
  - libnm/nm-ip4-config.h now uses     __NM_IP4_CONFIG_H__
  - src/nm-ip4-config.h now uses       __NETWORKMANAGER_IP4_CONFIG_H__

And likewise for all other headers.

The two non-"nm"-prefixed headers, libnm/NetworkManager.h and
src/NetworkManagerUtils.h are now __NETWORKMANAGER_H__ and
__NETWORKMANAGER_UTILS_H__ respectively, which, while not entirely
consistent with the general scheme, do still mostly make sense in
isolation.

For devices where we don't set the hardware address at construct time,
the first call to nm_device_update_hw_address() was hitting a
return-if-fail.

Also, when updating the hardware address, we were leaking the old
value.

Now that we have nm_utils_hwaddr_matches() for comparing addresses
(even when one is a string and the other binary), there are now places
where it's more convenient to store hardware addresses as strings
rather than binary, since we want them in string form for most
non-comparison purposes. So update for that.

In particular, this also changes nm_device_get_hw_address() to return
a string.

Also, simplify the update_permanent_hw_address() implementations by
assuming that they will only be called once. (Since they will.)

Add nm_utils_hwaddr_matches(), for comparing hardware addresses for
equality, allowing either binary or ASCII hardware addresses to be
passed, and handling the special rules for InfiniBand hardware
addresses automatically. Update code to use it.

Include <linux/if_ether.h> and <linux/if_infiniband.h> from
nm-utils.h, to get ETH_ALEN and INFINIBAND_ALEN, and remove those
includes (as well as <net/ethernet.h> and <netinet/ether.h>, and
various headers that had been included to get the ARPHRD_* constants)
from other files where they're not needed now.

Lots of old code used struct ether_addr to store hardware addresses,
and ether_aton() to parse them, but more recent code generally uses
guint8 arrays, and the nm_utils_hwaddr_* methods, to be able to share
code between ETH_ALEN and INFINIBAND_ALEN cases. So update the old
code to match the new. (In many places, this ends up getting rid of
casts between struct ether_addr and guint8* anyway.)

(Also, in some places, variables were switched from struct ether_addr
to guint8[] a while back, but some code still used "&" when referring
to them even though that's unnecessary now. Clean that up.)

Drop the arptype-based nm_utils_hwaddr funcs, and rename the
length-based ones to no longer have _len in their names. This also
switches nm_utils_hwaddr_atoba() to using a length rather than an
arptype, and adds a length argument to nm_utils_hwaddr_valid() (making
nm_utils_hwaddr_valid() now a replacement for nm_utils_hwaddr_aton()
in some places, where we were only using aton() to do validity
checking).