We will get the art if either:
    psz_arturl is NULL
    psz_arturl doesn't begin with "file://"

album art: the corrects picture URLs begin with "file://" else, we have to download/extract/look in the cache
sets the ArtworkURL to the file in cache also when it had been extracted previously

playlist/services_discovery.c: Isolate more the services_discovery code from the playlist code by having two separate header. Partly revert [22536].

services_discovery: storing the category & onelevel playlist items with the services_discovery_t is not needed anymore, simplify that.
put the services_discovery_t** in the public playlist_t to save one unchecked malloc() and the corresponding free()

One should never signal a condition without the corresponding lock:
 "if predictable scheduling behavior is required, then that mutex shall
  be locked    by    the    thread   calling   pthread_cond_broadcast()
  or pthread_cond_signal()." -- POSIX

This only fixes the most obvious cases. There might be others.

Fix [21193]

* Protect input item's meta through setters and getters. That allows tracking of input item meta info changes.
* vlc_meta_t gains a table for accessing its non-extra meta.

user stop or end of playlist).

field to "attachment://NAME" where NAME is an attachment filename
(returned by DEMUX_GET_ATTACHMENTS)
- Lock input_item_t every time we access p_meta fields (there is still a problem
as playlist code does not always do so...).
- Do not preparse item we have already played.
- Wait that the current playing item is meta parsed before fetching its cover.

This also seems to make the pre-existing Qt4 crash more obvious.

Revert [19273] because these asserts are meant to catch serious programming errors. Thanks zorglub for enlightning me.

work again yet )

(This way it matches input_CreateThread and fixes a memleak)
Control variables are now created even for preparse, only callback are not added.
(This fix use of uninitialized variables)

Unlock the playlist while waiting for input to finish so that input can freely use signal on the playlist whatever the context is (Closes:#937)

  releasing it. mutex locks /= 20 on a standard preparse run
* Only create absolutely necessary variables while preparsing
--> Preparse speed *= 4 (with item in disk cache of course)

* Do not rebuild playlist too much while adding a directory. Add a new flag
  to NodeCreate and Add to control this behaviour

* 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.

 - Remove a bunch of transition now-useless API.
 - Remove all playlist_Lock* functions. Matching functions now accept a
   b_locked parameter that should be set to VLC_TRUE if the playlist is
   locked when calling the function. The advantages are that it reduces
   the API bloat and that the b_locked flag can be propagated in the
   call stack
 - Remove useless playlist testsuite
 - Remove broken daap plugin (unmaintained wrt VLC API changes, relies on 
   an unmaintained library, probably unable to read content from new itunes, 
   ...). Implementations exist in rhythmbox, xmms2 and 
   daap-sharp, we should see if a proper lib exists or if we could 
   make one
 - Reduce verbosity a bit
 - Documentation

If the item is not to be preparsed but has enough meta, mark it as preparsed

This array is now usable as a reliable source of data for size
Use playlist_CurrentSize(p_playlist) to retrieve the size of the current playset.

Not tested heavily yet ...

For interaction implementers: you need to call playlist_Signal after changing the status of a dialog. Please see the diff for qt4/dialogs/interaction.cpp

 * Remove the random special case
 * Use the array of currently playing items for all cases
 * Convert array items to array API
 * Replace standard searches in sorted arrays by bsearches
 * Size is not yet fixed (next round).

Array
 * Add reset/value and bsearch functions
 * Add foreach helper

Todo: we should recheck cache just before downloading in case it has been downloaded while we were in the queue

Compile fix