With heavy use of conditionals, I broke Makefile.am for the ancient
automake version 1.6.  Instead of supporting this automake version
forever, I'm removing support for it now.  Since automake isn't
required on the build machine, nobody should have a serious problem
with that.

Since mpd-mk has become the "official" MPD, the rename from commit
ba892cbc can be reverted.

client->permission is a bit set, and should be unsigned.

Reduce two temporary variables to only one.

There is no sense in using the kernel's send buffer size (SO_SNDBUF)
for MPD's send buffer.  Convert it into a static buffer of 4 kB.

Use a literal in the struct declaration, and sizeof(client->buffer)
everywhere else.  Also shrink the buffer from 40 kB to 4 kB.  The
buffer must only be large enough to hold one line of input, and 4 kB
is still more than enough.

The buffer pointers must not exceed the buffer size.

Use ssize_t instead of int.

Commit 6eb62e47 didn't obey partial lines correctly: when a line
wasn't finished in one read, the first part was ignored when the rest
arrived.

Patch 25b5d90e broke zeroconf compilation, because it assumed that
$with_zeroconf was set to "yes", although it can be either "bonjour"
or "avahi".

[mk: fixed indent, changed copyright statement, added autoconf test,
fixed includes paths, fixed 2 gcc warnings, don't close input stream
twice]

Don't compile the sources of disabled decoder plugins at all, and
don't attempt to register these.

If a feature is disabled, don't compile the source file at all,
disable it completely in Makefile.am instead.

The nmemb argument isn't actually useful, and one of nmemb and size
was always passed as 1.  Remove it.

Provide a struct type which can be forward-declared.  The typedef
InputStream is deprecated now.

Wake up the player as soon as the decoder thread has entered its loop.
This fixes a dead lock when the input is blocking.

When adding a local file, clients have to use the "file" URI schema
described in RFC 1738 3.10.  By adding this schema to "urlhandlers", a
client can detect whether this feature is available.

The local variable "passcred" was only used by ucred code.

When building with the ancient automake 1.6 version, the following
errors occur:

 Makefile.am:5: invalid variable `doc_DATA'
 doc/Makefile.am:2: invalid variable `doc_DATA'

This patches renames some internal variables.

autotools are somewhat ugly, but that doesn't justify duplicating its
effort with another complex build system.

By default, glibc 2.8 hides struct ucred behind the _GNU_SOURCE
macro.  I don't want to enable that globally, because it may encourage
the use of non-portable functions.  Test if "struct ucred" is
available, and enable _GNU_SOURCE if required.

For details about that issue, see glib's bug database:

 http://sources.redhat.com/bugzilla/show_bug.cgi?id=6545

Make the configure.ac script more readable by wrapping lines and using
proper indentation.

Detect the following libraries with pkg-config: libshout, libid3tag,
libmad.

We're using GLib's character set conversion functions instead of iconv
now.

The undocumented command "add /" adds the full music database to the
playlist.  Don't interpret this special path as a local file path.

Allow a local user to not only add his own files, but also all
world-readable files (mode 0444).

Don't load non-regular files.

Clients which have authenticated via unix socket may add local files
to the MPD playlist, provided that they own the file.

Returning the playlist_result value from a command handler does not
make sense.  Call print_playlist_result() there, and forward its
return value.

Replace some complicated checks from addToPlaylist() to the simpler
function song_by_url().

Some functions assume that a song is not in the database when it is a
remote song.  Based on that, they decide whether they are responsible
for freeing the song struct.  Add a special function which checks
whether a song is in the database (currently equal to song_is_file()).

Enable authentication over unix sockets.  Store the client's uid in
the client struct.

Skip only the special directory entries "." and "..", don't skip all
other "hidden" files.

The switch from ogg.m4 to pkg-config intentionally disabled
libvorbisenc.  Enable it when shout_ogg is used.

This patch fixes several imports to use pkg-config instead of certain
esoteric tests.

string_toupper() and strDupToUpper() were not able to deal with
character sets other than US-ASCII.  Use GLib's g_utf8_casefold()
for strings.

Moved the musicDir variable and its initialization code from path.c to
mapper.c.

When the music directory is not mounted yet, let MPD start anyway.

GLib provides an easier API for character set conversion than iconv().
Use g_convert() / g_convert_with_fallback() for all character
conversions.  We should optimize the path.h API later to return a
newly allocated buffer, so we can just pass GLib's return value.

GLib is a nice and portable utility library.  We are going to use it
from now on, and eliminate a lot of duplicated code from MPD.  Why
invent the wheel again and again?