This simplifies callbacks a bit, and fixes a race condition.

it is needed to pass from input_item_t to playlist_item_t
 for this variable only (others directly provide playlist_item_t)

Make sure that the playlist item has been preparsed first (and don't get stuck in an infinite loop). Note that libs/input.c is a mess and would need to be cleanup before we release 1.1.

New dumpmeta lua interface module to dump a file's meta data on stdout/stderr (I'll let you figure out which one it is). Use as: vlc -I lua --lua-intf dumpmeta filename.mp3

This is not used. The VLC_VAR_VARIABLE type is used by "navigation" only
in a different way (basically, it is a string).

(Fortunately, both corresponded to the same location.)

For example, if runing script <user dir>/lua/intf/script.lua, the following paths will be added:
  <user dir>/lua/modules/?.lua
  <user dir>/lua/intf/modules/?.lua
  <share dir>/lua/modules/?.lua
  <share dir>/lua/intf/modules/?.lua

If runing script <share dir>/lua/intf/script.lua, the following paths will be added:
  <share dir>/lua/modules/?.lua
  <share dir>/lua/intf/modules/?.lua

When scanning multiple lua scripts, create a new lua_State for each script. This will prevent data corruption from a previous script affecting subsequent scripts.

This patch
  - ensure that current playing item is properly detected
  - deactivate item changes since it is wrongly implemented
    (i_id from input_item_t and playlist_item_t are compared,
     which is wrong)

I didn't find any reason to do it, and it slows closing quite a lot,
if you know why we should do that, please speak up etc.

It closes #2349.

It simplify the flac decoder code.
It fixes the build of the packetizer when flac is disabled.
It makes the flac packetizer behaviour independant of the flac decoder presence.