[omxplayer] When setting fullscreen flag we don't want noaspect

We set the fullscreen on 3d videos to avoid scaling breaking the 3d affect.
However we also set the noaspect flag which means widescreen videos (e.g. 1920x800) will get stretched vertically which is unwanted.
[hifiberry] Hack: force it to be recognised as IEC958 capable to enable passthrough options
[PiSink] Fix some issues with buffering and multichannel

Also support AE_FMT_FLOAT and AE_FMT_S32 (requires updated firmware)
Buffer is increased to 100ms to reduce chance of underrun.
[dvdplayer] Use inexact seeking like omxplayer
[omxcodec] More care with dropping frames quickly
- ensure to announce airtunes before airplay via zeroconf (makes it more likely that ios7 clients detect us correctly at the first shot)
- add method to reannounce already published services
- reannounce airplay service every 10 secs (fixes ios7 clients not detecting us when their wlan was asleep or they saw the airplay announcement before the airtunes annoncement)