this patch features several cleanups and bugfixes for the sequencer:

this patch features several cleanups and bugfixes for the sequencer:
- blur works again (this was a serious bug in gamwarp...)
- seperates all sequence effects into a seperate file with a clean interface
- thereby fixing some obscure segfaults
- seperates the scope views into a seperate file
- adds float support to all effects and scope views
- removes a bad level call to open_plugin_seq
- FFMPEG seeking improved a lot.
- FFMPEG compiles with debian sarge version cleanly
- Makes hdaudio seek and resample code really work