Blender Git Loki

==Sequencer==
- Added early-out optimisation to add-effect (the case, where fac == 0)
- Bugfixes:
* hddaudio: ffmpeg does not seek always to the correct frame,
if the SEEK_BACKWARD flag is used. Now we account for this and
seek a little bit further... (hack, urghs)
* hddaudio: on long timelines, the new seek code didn't work
(forgot a long long cast)
* the audio mixdown code now also calculates meta-strip IPOs