Revert the Codec Kit.

All of Barrett's individual reverts have been squashed into this
one commit, save a few actual bugfixes.

Change-Id: Ib0a7d0a841d3ac40b1fca7372c58b7f9229bd1f0

PluginManager: Move reference counting in the MediaPlugin

* Ideally we should support this feature by default to allow
future improvements to the plugins management.
* Fixes the major memory corruption that lead to various
crashes on exit in MediaPlayer.

PluginManger: Remove BReferenceable and add locking

StreamerPlugin: Add reference count

* Keep the Streamer around until everyone released it.

Streaming: Use const reference in place of copying

* Thanks to Markus for reporting.

Streaming: Remove any pointer BUrl argument

* There's no need to pass BUrl by pointer, this is
potentially dangerous and leaky without any advantage,
copying is definitely safer.

StreamerPlugin: Use BDataIO as base interface

* There's no need to force the streamer plugin to use a
BMediaIO. This class is supplied to accomodate more smart uses,
but in certain cases it makes just things more complex. If a
plugin doesn't need to have an internal caching method, then it
will be simpler to implement a block-consuming BDataIO and let
the internal BMediaIOWrapper to deal with caching.

Move MediaIO in it's own header

Finalize StreamerPlugin

* Add cpp file.
* Make Sniff virtual.

Add initial design of StreamerPlugin