To demonstrate the new I/O thread.  libsoup is well-integrated into
the GLib main loop, which made this plugin pretty easy to write.

As a side effect, we have to initialize the I/O thread in all debug
programs that use the input API.

Try to eliminate the remaining blocking I/O.

Eliminate duplicate code.

Better than dereferencing NULL.

No point in returning true, and checking that.

.. and not -1, which is "true".

Allocate objects on the stack to reduce heap overhead.

Not unsigned char.  Eliminate useless casts.

Only used internally.

This defaults to "false" when the method pointer is NULL.

Check if the stream is suspended; wake up the main loop when it
becomes suspended.

Not a bool.

Unlock the mainloop in all code paths.

This warning should only be logged when we really received something.
When the client disconnects, G_IO_IN is triggered, and the read
returns G_IO_STATUS_EOF.

Move the variable "vbr_update_acc" into the #ifdef block.

Conflicts:
	src/player_thread.c
	src/playlist_control.c

There's no bzero() on WIN32.

Be portable on WIN32.

In the "vorbis" plugin, this is a copy of the old flush() method,
while flush() gets a lot of code remove, it just sets the "flush" flag
and nothing else.  It doesn't start a new stream now, which should fix
a few problems in some players.

Enable gcc optimizations.

The method may take longer, and we shouldn't be holding the lock.