unrelated changes that ended up being more trouble to commit separate...
- removed BLI_split_dirfile(), was nasty, occasionaly modifying the source string, it could create directories and used the $CWD in some cases. was only used in 2 places in filesel.c, if this gives problems can address without bringing back this function.
renamed BLI_split_dirfile_basic --> BLI_split_dirfile
- view3d_operator_needs_opengl was being called for offscreen render when it wasnt needed.