Blender Git Loki

Big Commit.

Now time-markers work in all time-related spaces (i.e. Ipo,
Action Editor, NLA editor, TimeLine, Sound). The hotkeys and
functionality set should be the same for each of these modes
(with a few exceptions still). I've had to change a few hotkeys
here and there, so hopefully they aren't too bad.

Marker Operations:
MKEY - Add Marker
SHIFT MKEY - Rename marker (was CTRL MKEY)
XKEY - Delete Marker
PAGE UP - Jump to next marker
PAGE DOWN - Jump to previous marker
CTRL A - Select all markers
SHIFT G - Transform markers (NLA, IPO, Action)
G - Transform markers (Sound, Timeline)
CTRL SHIFT D - Duplicate markers (NLA, IPO, Action)
SHIFT D - Duplicate markers (Sound, Timeline)
BKEY - select markers and other keyframes (if any)

I've also made a few little tool additions to NLA and Action editors:
* NLA editor - Snap To Frame.
Now with the option to offset strip so that it starts at the current frame.
Added menus for this.
* Action editor - Snap To Frame
A few new menus for this too