* Brought back backend for editing keyframes IPO/IPO-Curves. Did some refactoring work here that will still have to be verified when operators using them are added.
* Animation channel filtering code now returns the number of channels filtered (for Action Editor to set totrect of channels - TODO still!)
* View2D - made function to check if mouse is in View2D scrollers an API function
* Renamed keyframe related files. The old names were too clumsy.
* Started porting click-select operators for Action Editor. These don't work currently, as the events are being stolen by the markers. This needs to be fixed ASAP.
* Added new 'Animation' submodule under Editors. This will be used to house all code + features that are used by many different Animation Editors (Action/Dopesheet and IPO) as well as other parts of Blender.
* Added back some of the core code need by the Action/Dopesheet editor, which will also be used by IPO Editor.
* Brought back file for keyframing management code (i.e. keyframing.c), but there's still quite a lot of missing stuff that I'll need to restore, so in the meantime, it's #if 0'd out.
* Moved markers code to this new module (I'm not sure whether SVN will recognise this change, as TortoiseSVN doesn't seem to have any obvious copy/move commands)
