This patch completes the configuration support.

Don't call g_error(), which will abort the process and dump core.

This patch does not affect all the config_get_X() functions.  These
need some more refactoring.

This option was deprecated by the 0.15 release.  This patch makes this
option invalid.

The functions were not "const" (they examined values pointed
by arguments passed to them, quoting gcc's doc: "Note that
a function that has pointer arguments and examines the data
pointed to must _not_ be declared 'const'.") but rather
"pure" and still not all of them.

Note also, that even some of the functions declared "pure"
are not pure, however, due to reasons stated in source code
the attribute has been kept.

The "group" configuration option is similar to "user" as it
sets user set what group MPD shall run as.  With "user"
option, MPD changed GID to the GID of the user, however,
more control could be desired.

Moreover, the patch changes the way of checking whether no
setuid(2)/setgid(2) is required -- previously user names
were compered, now UID and GIDs are compered (ie. the one we
already have (getuid(2)/getgid(2)) with the one we want to
change to).

Add the "const" attribute to functions when their return value only
depends on parameters.  This allows gcc to eliminate some function
calls.

This GQuark will be used for GErrors related to malformed
configuration.

Instead of returning an artificial three-state integer, return a
"success" value and put the boolean value into a "bool" pointer.
That's a little bit more overhead, but an API which looks more
natural.

This function is unused.

The top-level "mixer_device" and "mixer_control" options have been
deprecated by MPD 0.15, and it's safe to remove them in MPD 0.16.

Renamed all remaining CamelCase functions.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

Allow input plugins to configure with an "input" block in mpd.conf.
Also allow the user to disable a plugin completely.

The "decoder" configuration block may contain the configuration of one
decoder plugin.

The function config_add_param() allows adding new configuration
parameters.

All config_get_block_*() functions should accept constant config_param
pointers.

Don't declare and export variables specific to stored playlists in
playlist.c/playlist.h.

This convenience function parses a configuration value into a positive
integer.  It aborts if parsing fails.

"Stickers" are pieces of information attached to existing MPD objects
(e.g. song files, directories, albums).  Clients can create arbitrary
name/value pairs.  MPD itself does not assume any special meaning in
them.

Eliminate some more getBlockParam() invocations.

This replaces lots of getBlockParam() invocations.

Use config_get_path() instead in mapper.c.

config_get_path() is an simpler interface than parseConfigFilePath().

Don't return a writable pointer.

No "force" parameter, pass a default value instead.

Renamed functions, types, variables.

removing mixer_reconfigure memmory leak, fixing configure of alsa and oss mixer (passing parameters)

The configuration options "follow_outside_symlinks" and
"follow_inside_symlinks" let the user control whether MPD should
follow symbolic links in the music directory.

[mk: converted variables to "bool"; moved configuration to
update_global_init()]

In contrast to, getBoolConfigParam(), config_get_bool() properly
returns a "bool" value.  In case of "unset", it returns the default
value provided by the caller.

"LOG_H" is a macro which is also used by ffmpeg/log.h.  This is
ffmpeg's fault, because short macros should be reserved for
applications, but since it's always a good idea to choose prefixed
macro names, even for applications, we are going to do that in MPD.

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