Send another "magic" MIME type when the byte order must be reversed.
This also fixes byte order issues when big-endian was involved (input
data or host byte order) - that was completely broken.

Copy the reason_phrase from the SoupMessage, and check for transport
errors in the session callback.

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.

Fix memory leak.

libsoup's asynchronous API is not thread safe.  By moving the calls
into the I/O thread, several crash bugs will be fixed.

Add the "complete" attribute, and set it in _session_callback().
_close() waits for it to become true.

Add attribute postponed_error, pass this GError to the caller.

Fix deadlock.

We'll add proper locking now, and there's no need to carry this
duplicate flag.

To report failures to callers who don't use _buffer().

Avoid recursive deadlock in _session_callback().

Pausing and resuming after every little chunk adds lots of overhead.
Add a lower level for resuming the stream.

curl_easy_pause(CURLPAUSE_CONT) may have added enough data to go into
pause again.

Call _update_fds() directly.  This is possible because it's only
called from within the I/O thread.

Fix deadlock.

Reduce heap usage by reducing the number of malloc() / free() calls.

The global data structures are now lock-free, because they are
accessed only from the I/O thread.  By using per-request locks, we
have finer grained locking, preparing for locks shared with the
client.

This adds some overheads for indirect calls to the I/O thread, but
reduces the amount of global locks.  Next step will be switching to
per-request locks.

Move the assignment to _request_done(), right before the GCond is
signalled.  This might fix spurious wakeups.

This is a trivial function.  Merge some duplicate code, e.g. the
g_cond_broadcast() call.

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

Be sure to stop the operation at some point when the server isn't
responding.

Background buffering and better timeout handling.  This patch sort of
obsoletes the input_plugin method buffer().

Assume the flag is true when the "easy" CURL handle is NULL.  That
way, we don't need to keep track if CURL has sent us the "DONE"
information yet.

Release it immediately when end-of-file has been reached.  We don't
need that handle anymore, because the rest is delivered from the
buffers.

Allow closing the handle while preserving the remaining buffers.

Remove a cast.

Let the caller know what happened, he's responsible for logging.

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.