Unfortunately, $(AM_CPPFLAGS) gets overridden by per-target _CPPFLAGS
variables, which $(INCLUDES) did not, so this requires some additional
changes.

In most places, I have just gotten rid of the per-target _CPPFLAGS
variables; in directories with a single target, the per-target
variable is unnecessary, and in directories with multiple targets, the
per-target variable is often undesirable, since it forces some files
to be compiled twice, even though there ends up being no difference
between the two files.

Although having different parts of NM in different subdirectories
keeps the source tree neat, it has made the build messy, particularly
because of cross-dependencies between the subdirs.

Reorganize to build all of the pieces of the NetworkManager binary
from src/Makefile, and only use recursive make for test programs,
helper binaries, and plugins.

As part of this, get rid of all the per-directory convenience
libraries, and switch to building a single top-level
libNetworkManager.la, containing everything except main.c, which all
of the test programs can then link against.

Use g_test_add_func() and g_test_add_data_func() to simplify the test
cases, getting rid of the GLIB_CHECK_VERSION calls in the process.

Use --enable-doc and --enable-tests instead of --with-docs and
--with-tests. This is consistent with other features and with
--enable-gtk-doc option. Support current variants as fallback.

Don't build tests unless --enable-tests is specified.

nm-version.h is in ${top_builddir}/include.

Due to an error in the loop logic, if there were no connections yet (like
a fresh install or a livecd or whatever) no default name would be returned
and thus ethernet devices wouldn't come up automatically.  Fix that loop
error and add testcases for it.