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

playlist/services_discovery.c: Attempt at removing also node as well as regular items. Need some testing with the hal services_discovery module.

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()

macosx: playlistinfo.m. small typo which caused ObjC exception and froze interface updates and screensaver management, etc...

Qt4 - use a docked playlist, remove dead code, don't reinvent the wheel, remove the behaviour where media library hides the video. Don't split the menu between two dialogs, this is weird and anti sane GUI guidelines.
Use enums when you can.
Add the popup menu to the always video cone.
And more...

services_discovery: stores the category & onelevel playlist_item_t* in the services_discovery_t structure
simplify upnp* and hal modules

(Still MIDI tempo is critically missing)

width and height are specified in the subtitles stream. This may
result in chunkier text in some instances, but it should get it
back on screen at least. Will look into smoothing it out next.

the mkv demuxer could double checked it)

(Still missing the ES out so pretty useless, but got to sleep now)

macosx: Multiple GUI improvements follow j-b's and my approach to synchronise the QT4 and OSX intfs, more to come
- "Use DVD Menus" is inverted now, so it's "No DVD Menus"
- 3 dots at the end of a menu-item's caption mean that the entry will trigger a window (following Apple's HIGL)
- removed the entries for "Report a Bug" and "License". The first isn't necessary as we got enough of them and users doing useable reports know how to do, the latter will re-appear in the to-be-re-designed About panel.
- additionally, removed useless occurences of vlc_bool_t in favour of BOOL
- preparations to add fps to Statistics