Sequence editor

Improvements 2.49b

IPO curve-deletion resulted in non-working effect
easy retiming only allowed enlarging of strips, now shrinking is also possible (easy retiming: use the right display handle of input strip and shrink or enlarge, will make the speed of the strip exactly fit the effect strip's length)
frames after end-of-display of input strips can now be accessed.
frame blending can now be done on more than two frames, enabling really fine grained motion blur if you speed up a sequence with high factors (bigger than two).
Scene-Strip rendering with compositor scenes failed, if they had no camera attached.
Fixed hdd-audio for sample formats other than 16 bit (8 bit eg).

Scrubbing sound could create an echo
Fixed two cases with crashing FFMPEG
"duplicate strip" always increase the user count for ipo now.
Work around crash in dv-reader of ffmpeg, that can happen, if some frames don't contain audio
free_imbuf_seq() didn't free all scenes. That will lead to steady memory growth in case of nested timelines with several scenes.
Big Proxy fixes, addressing hopefully most complaints on mailing list and in tracker
Fixed color balance tool. Problem was: we pretended to do Lift/Gamma/Gain, but in reality we did (1-Offset)/Power/Slope. (slightly modified ASC CDL). So now, the GUI is able to switch modes between ASC CDL-mode and real Lift/Gamma/Gain.
Syncing audio to 3D window works again

Sequencer: effect strips had no filter option, which was therefore added. So you can apply color balance on effect filter output