AC_CHECK_HEADERS defines HAVE_LOCALE_H, so we don't have to manually
define HAVE_LOCALE.

Make db_load(), db_save() and db_check() return bool instead of int.

For updating the database, directory_update_init() should be called
explicitly.

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

There is only one location using PIPE_EVENT_SIGNAL: to synchronize
player_command() with player_command_finished().  Use the "notify"
library instead of the event_pipe here.

Make the event_pipe (formerly main_notify) send/receive a set of
events, with a callback for each one.

The default event PIPE_EVENT_SIGNAL does not have a callback.  It
is still there for waking up the main thread, when it is waiting for
the player thread.

Continuing the previous patch.

We are going to migrate away from the concept of notifying the main
thread.  There should be events sent to it instead.  This patch starts
a series to implement that.

With the GLib main loop, the client manager can install its own event
in case a client is expired.  No need for main.c to call
client_manager_expire() manually.

Other libraries may need to access the main_loop reference, to add or
remove events, or to call g_main_loop_quit().

This is a rather huge patch, which unfortunately cannot be splitted.

Instead of using our custom ioops.h library, convert everything to use
the GLib main loop.

redirect_stdin() is a daemonization function, and disconnecting from
the standard input is always a good idea for MPD.

Disable changeToUser(), daemonize(), killFromPidFile().

Removed the fallback setenv() implementation for solaris.

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

The logging library currently has 3 constructor functions: initLog(),
open_log_files(), setup_log_output(), called in this order.  Merged
the first two.

When there are no archive plugins, we do not need the archive API at
all.  Drop all its overhead.

Those two functions are called when MPD starts and exits.  It allows
the update library to perform global initialization and
deinitialization.  The implementations are currently empty.

Make valgrind happier.

When MPD quits in a non-clean way, the state file isn't written, and
on the next start, MPD time warps to the previous clean shutdown.
Save the state file every 5 minutes; this will probably be
configurable at a later time.

Note that we don't set a wakeup timer for that: when there is no MPD
traffic, MPD won't wake up to save the state file.  This minor bug is
tolerated, because usually there is no change in MPD's state when the
main thread is idle.

Renamed functions and variables.

No CamelCase file names.

Using the logging library here is inappropriate.

The warning buffer is a complex piece of code for no good reason.
Remove it and find a better solution, e.g. open the log file earlier.

Initialize libc's locale functions.  Currently, we are only interested
in LC_CTYPE (character classification), because this is what is used
by GLib's g_get_charset().

Rename variables and functions.

Call g_thread_init() from main() to enable the GLib features which
make it thread safe.

Removed closeAllFDs().  The caller is responsible for closing all file
handles.

Rename all functions to the new prefix.