tta & ffmpeg: remove unneeded "meta reader" loading
tta didn't use anyway, and ffmpeg uses information from libavcodec

FcConfigSetCurrent( p_sys->p_fontconfig ) is useless since we already use that configuration, and it will destroy it.
So, when we want to destroy it again when freetype module is closed, CRASH.

 var_CreateGetBool( p_demux, "meta-preparsed" )
(The demuxer should NOT overwrite it)
subtitle: do not look for p_input when not necessary.

control/video: find the vout anywhere, so the one spawned by audio output (audio visualization) can be found. fix #1202

taglib: warn the user when the embedded image is invalid (i.e. was embedded by a broken version of iTunes)

Don't use strerror()
The error message displayed can be useful to debugging purposes.

taglib: Supports in ogg/vorbis base64 encoded embedded album art with COVERARTMIME & COVERART comments.
    Use TagLib namespace for better code readability.

demuxers: Adds attachments support for ogg.
    Fix potential memleaks.

notify: unref the notification popup after we have finished using it. fix a big memory leak, and potential crashes.

control/media_instance.c: Fix a segfault caused by libvlc_media_instance_release. (Patch by Enrique Osuna).