Move most functions into separate files.
File sequencer.c is reserved for alloc, free and duplicating functions.
There should be no functional changes.
Variables renaned:
- cfra -> timeline_frame
- nr -> frame index
- cfra_over -> overlap_frame
Function seq_give_stripelem_index was renamed to seq_give_frame_index.
Move functions closely related to rendering images and proxies into
render.c and proxy.c files. render.h and proxy.h are created for
functions used internally.
There should be no functional changes.
Intern definitions are moved to sequencer/intern/sequencer.h
BKE_sequencer.h was also cleaned up a bit to make sure that functions
and structs are in correct category.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D9259
