Hide the definition from C code, to prepare the transition to C++.

Move code from the Vorbis decoder plugin.

MPD requires GLib 2.16.

Add GMutex, GCond attributes which will be used by callers to
conditionally wait on the stream.

Remove the (now-useless) plugin method buffer(), wait on GCond
instead.  Lock the input_stream before each method call.  Do the same
with the playlist plugins.

To check for errors without reading.  The decoder thread wants to do
that, before it passes the input stream to the plugin.

Update the struct attributes, important for facades like the "rewind"
plugin.  To replace buffer().

All close() implementations must call this method.

Major API redesign: don't let the caller allocate the input_stream
object.  Let each input plugin allocate its own (derived/extended)
input_stream pointer.  The "data" attribute can now be removed, and
all input plugins simply cast the input_stream pointer to their own
structure (with an "struct input_stream base" as the first attribute).

After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.

Drop the required GLib version from 2.16 to 2.12, because many current
systems still don't have GLib 2.16.  This requires several new
compatibility functions in glib_compat.h.

The "off_t" type may change when you enable or disable large file
support on 32 bit platforms.  This caused severe ABI problems within
MPD when we enabled LFS for the first time: two sources included
config.h and sys/types.h in different order, and had different off_t
sizes - leading to memory corruption because of ABI incompatibility.
This patch attempts to get rid of all public "off_t" uses: it removes
"off_t" from the input_stream ABI/API, and switches to GLib's 64 bit
"goffset" type.  This may hurt 32 bit embedded platforms a tiny bit,
but that's not even measurable.

AC_SYS_LARGEFILE defines macros for config.h.  If we don't include
config.h, we don't get large file support.

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.

Start to separate private from public input_stream API.

The open_stream() method opens the input_stream.  This allows the
archive plugin to do its own initialization, and it also allows it to
use input_stream.data.  We can remove input_stream.archive now, which
was unnatural to have in the first place.

The tag() method reads a tag from the stream.  This replaces the
meta_name and meta_title attributes.

"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.

size_t and long aren't 64 bit safe (i.e. files larger than 2 GB on a
32 bit OS).  Use off_t instead, which is a 64 bit integer if compiled
with large file support.

For boolean values and success flags, use bool instead of integer (1/0
for true/false, 0/-1 for success/failure).

close() shouldn't fail with read-only streams.

Instead of managing a set of method pointers in each input_stream
struct, move these into the new input_plugin struct.  Each
input_stream has only a pointer to the plugin struct.  Pointers to all
implementations are kept in the array "input_plugins".

Renamed all functions and variables.

Everybody should use struct input_stream.

Renamed inputStream.c and inputStream_file.c.

The hook input_stream_global_finish() deinitializes global structures
of all input stream implementations.

The typedefs aren't using by anybody but struct input_stream.  Remove
them and declare the method type within struct input_stream.

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