- "gsystem-local-alloc.h" and <gio/gio.h> are already included via
"nm-default.h". No need to include them separately.
- include "nm-macros-internal.h" via "nm-default.h" and drop all
explict includes.
- in the modified files, ensure that we always include "config.h"
and "nm-default.h" first. As second, include the header file
for the current source file (if applicable). Then follow external
includes and finally internal nm includes.
- include nm headers inside source code files with quotes
- internal header files don't need to include default headers.
They can savely assume that "nm-default.h" is already included
and with it glib, nm-glib.h, nm-macros-internal.h, etc.
Up to now, the "include" directory contained (only) header files that were
used project-wide by libs, core, clients, et al.
Since the directory now also contains a non-header file, the "include"
name is misleading. Instead of adding yet another directory that is
project-wide, with non-header-only content, rename the "include"
directory to "shared".
