This improves readability a lot and prevent us from reinventing the wheel.

    mvar_InfoSetNew(): removes unused parameter
    avoids unused parameter warnings from httpd callbacks

Missing some cases that I could not test.
Also ffmpeg/chroma.c is locked, so I can but leave it broken.
Fix is for the remaining modules is obvious and the issue is easy to detect.

heavy simplification, and fix(/remove) piles of error cases.
Server gets to choose the charset anyway.

Please fix it *** IF YOU KNOW WHAT YOU ARE DOING ***

* Headers in include must contain the structures and prototypes needed
  by the plugins and should be named vlc_*.
* Headers in include/vlc must contain the structures and prototypes
  needed by external libvlc clients

* Moved and renamed some things in headers. 
   - Removed vlc_cpu.h, vlc_error.h (merged in vlc_common)
   - Removed snapshot.h (merged in vlc_vout.h)
   - Removed vlc_spu.h (merged in vlc_osd.h)
   - Removed intf_eject.h and vlc_interaction.h (merged in vlc_interface)
   - Moved all internal headers to src
   - Merged vlc_video.h and video_output.h and move private things to src
   - Removed vlc/intf.h, vlc/aout.h, vlc/vout.h, vlc/decoder.h and vlc/input.h
     (meta headers for use in modules, and often implying too large 
     dependencies)
* Removed some useless dependencies
* Unexported a bunch of functions and structures used only in src/
  (--> Still some work here)
* Finally made input_thread_t and input_source_t (mostly) private. 
  Added input_GetItem to fetch the input_item of an input_thread
* Cleaned up deprecated entries in vlc_symbols.h and bumped up symbol 
  prefix

This commit has a 99% probability of breaking the build, 0.1% of killing
your cat and 0% of getting you hot chicks.

What is currently broken:
 * Some playlist demuxers (shout, dvb and pls)
 * DAAP
 * BeOS playlist
 * GPE playlist, I suppose

What has some trouble:
 * Meta handling in several demuxers (most notably TS)
 * Skins2 playlist (doesn't refresh correctly)
 * OS X playlist (see bigben's latest commits)

* rpn.c: add "services_discovery_add", "services_discovery_remove" and "services_discovery_is_loaded" rpn functions.
* macro.c, http.h, mvar.c: add new "object" param2 for foreach macro. It gives a list of all objects matching a capability.

                              (instead of stoping after a depth of 2)

src/misc/vlm.c : minor instance information reporting change

* Free scandir results when we are done with them. Issue pointed out by jmvallat_vlc at mac dot com.

   drive letters because it seems to cause problems with removable devices.

   allows to call vlc_readdir_wrapper("\\") and get a list of Windows drives.
   This is a bit kludgy but so convenient to change drives under Windows.
 * modules/control/http: Adapted to use vlc_readdir_wrapper in foreach
   directory. Thou shalt escape all exported functions with E_() to avoid
   potential namespace collisions !
 * po: Re-run make update-po since POTFILES.in has changed.

   indicate which object we are playing with (for instance 'VLC_OBJECT_INPUT'
   or 'VLC_OBJECT_PLAYLIST'). Espace \ in addslashes.
 * modules/control/http: Factorized and simplified the RealPath() stuff.
   Fixed a few hardcoded '/' as a path separator.