Gooseberry request, snap frame marker during frame setting by holding
ctrl key

Merge branch 'master' into terrible_consequencer

Conflicts:
source/blender/editors/space_sequencer/sequencer_draw.c

Snap to left-right based on position of mouse relative to selection.

Support endpoint snapping correctly.

First iteration of snapping based on strips - will be improved based on
imput from Mathieu.

fix some errors

Merge branch 'master' into terrible_consequencer

Conflicts:
source/blender/editors/include/UI_view2d.h
source/blender/editors/space_sequencer/sequencer_edit.c

Merge branch 'master' into terrible_consequencer

Conflicts:
source/blender/editors/space_sequencer/sequencer_edit.c
source/blender/editors/space_sequencer/sequencer_ops.c

Trim tool:

Support metastrips and multiple strips at once.

WIP support for meta trimming

Merge branch 'master' into terrible_consequencer

Undo previous changes to sound.

The sound system really needs better design for the sequencer and
patching it up now won't really help us in the long run.

Also the sequencer kept leaking file descriptors when preserving
the audio handlles on undo making the branch unusable on mac and
windows.

It's almost certain patching over this will lead to more trouble, better
handle it separately and keep the system working for now.

Kept threaded loading of waveforms since we control the file input
directly there and leads to nice speedup, but we still clear the whole
sound + the waveform on undo, which is pretty bad.

Merge branch 'master' into terrible_consequencer

Yet another attempt to solve OSX issues, restore sequence sounds too, or
sounds get added to two sequence and file descriptors leak

Minor corrections to the types

New data types for sequencer.

Uses struct hierarchies to reduce the data used per strip.

Also changed sequence -> strip. Might be better to use NSequence for
editing as well.

Merge branch 'master' into terrible_consequencer

Gooseberry request: Backdrop for sequencer.

Add missing notification for trimming to stop showing the extensions

Gooseberry request, hide the extensions except when trimming.