Get rid of CamelCase, and don't use a typedef, so we can
forward-declare it, and unclutter the include dependencies.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7361 09075e82-0dd4-0310-85a5-a0d7c8717e4f

Try to only include headers which are really needed.  We should
particularly check all "headers including other headers".  The
long-term goal is to have a manageable, small API for plugins
(decoders, output) without so many mpd internals cluttering the
namespace.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7319 09075e82-0dd4-0310-85a5-a0d7c8717e4f

This will make refactoring features easier, especially now that
pthreads support and larger refactorings are on the horizon.

Hopefully, this will make porting to other platforms (even
non-UNIX-like ones for masochists) easier, too.

os_compat.h will house all the #includes for system headers
considered to be the "core" of MPD.  Headers for optional
features will be left to individual source files.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7130 09075e82-0dd4-0310-85a5-a0d7c8717e4f

the force flag will issue FATAL() if an invalid value is
specified

git-svn-id: https://svn.musicpd.org/mpd/trunk@6857 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@6468 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@5834 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@4489 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@4474 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@4425 09075e82-0dd4-0310-85a5-a0d7c8717e4f