Use GLIB_CHECK_VERSION() instead of manually checking
GLIB_MAJOR_VERSION, ...

Print the list of suffixes supported by each decoder, instead of
prining a list of all suffixes of all decoders with duplicates.

Renamed functions, types, variables.

mpd uses some additional files to work, such as pid_file, state_file,
db_file, etc. when running mpd as non-root user, it is often that those
files end in ~/.mpd

in that case, we end up with 2 entries in a user's home, .mpdconf and
.mpd - which clutters homedirs.

this patch allows ~/.mpd/mpd.conf as an alternative to ~/.mpdconf,
allowing for a cleaner homedir

Start the daemon after --create-db.  This makes --create-db a flag
which discards the old database and starts with a fresh one.

Don't start the daemon when MPD is called with "--version".

Only include headers which are really needed.  os_compat.h aimed to
make MPD easily portable, but was never actually made portable.

Removed the "error_file" option.  There is only one log file now.  If
a user wants to see only the errors, he should configure a log_level.

Build the path with g_build_filename().  Also use g_get_home_dir() and
g_file_test().

Eliminate duplicated code.  The GLib code is much more mature than
MPD's custom parser.

Prepare for the migration to the GLib option parser, which uses
gboolean for flags.