fixes a big crasher in the DestroyFilter of the logo video filter

* 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.

Also, make it clearer what is shared and instance-specific

So,
libvlc_t ==> libvlc_global_t
vlc_t ==> libvlc_int_t (internal instance)

p_object->p_libvlc ==> p_object->p_libvlc_globale
p_object->p_vlc ==> p_object->p_libvlc

VLC_OBJECT_VLC ==> VLC_OBJECT_LIBVLC

And by the way, there is some cleanup required :) (ie, some things are created in the global object instead of the instance-specific one)

loops through these. The syntax is <file>[,[<delay in ms>][,[<alpha>]]][;...]
Idea (and some parts of the code) by markfm

Note:
The vout-filter segfaults upon destruction but i don't understand why...
could someone have a look ?

 - Missing value lists
 - advanced / non-advanced problems
 - description problems
 - tyops

Merged OSD functionality on the same core functions. All OSD functionality is described in include/vlc_osd.h now, which entirely replace include/osd.h. The file src/video_output/video_widgets.c uses functionality from src/osd/osd_widgets.c now.

(da big courmischage)

Make logo-x, logo-y operate relative to upper left corner.  logo-x/-y/-position/-transparency accessible via rc

+ put access and demux in the right place

Fix a bug with preferences
Added some more names
Use shortname to store the name

* Each module can declare a "human-readable short name" with set_name
* Modules are sorted by category (set_category, set_subcategory).
  Modules configs can be separated by set_section()
* Separated audio-filter and audio-visual
* Separated extraintf and control
* New command and widget : add_module_list() for comma-separated modules
* Vfilters now use "," as separator

* modules/video_filter/logo.c: new --logo-position option (by default the logo is displayed on the top right)