* backported: [15596]-[15603],[15605]-[15608],[15611],[15615],[15616],[15626]-[15628], [15631],[15636],[15637],[15639],[15643],[15647]-[15651],[15654],[15658],[15662],[15668],[15669],[15673]-[15675],[15678],[15680]-[15682],[15684],[15689]-[15700]
as well as the intf.m part of [15638]

The interaction framework updates and playlist changes were left out

* basic support for SSA formatted subs. (disable with --no-subsdec-formatted option)
* changes to freetype renderer to support the font color, size and alpha options of text_style_t (other options are possible, just not implemented yet. Full text_style_t support requires a more advanced renderer though. )
* changes to modules to support text_style_t instead of the old sub options.
* Some changes to subsdec to only iconv to UTF-8 if source is !UTF-8.

refs #82

not supported are style runs (styles on substrings).

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)

* modules/stream_out/transcode.c: re-use the SPU engine.
* src/video_output/vout_subpictures.c: support for resizing subpictures.

When you want to use OSD, you have to register an OSD channel, by calling
vout_RegisterOSDChannel, then pass it to vout_CreateSubPicture.
There is a particular channel, DEFAULT_CHANNEL that can be used for
general purpose.
See modules/control/hotkeys.c for an example.

* added i_channel and i_content properties to subpicture_t
* p_last_osd_message is no more used

An OSD channel can contain simultaneously an OSD text and an OSD widget.

  - added browse-follow-anchor, browse-go-back and browse-go-forward
    callbacks
  - will not display clip description as subtitles if
    intf-displays-cmml-description variable is set on main interface
    thread
  - bugfix for web browser launching on Mac OS X