Orange: more exr & imbuf cleanup

- Reading exr images now goes OK. I've unified the code for reading
  'half' and 'float' (was nicely possible!). And removed useless copying
  of data around.

- Fixed bug in allocating new rects, like for making mipmaps. flag issues.

- filter code accidentally incremented wrong pointer (crash on mipmap too)

source/blender/blenkernel/intern/writeavi.c

@@ -43,9 +43,6 @@
 #include "BKE_bad_level_calls.h"
 #include "BKE_global.h"
 
-#include "IMB_imbuf_types.h"
-#include "IMB_imbuf.h"
-
 /* RPW 11-21-2002 */
 #include "DNA_scene_types.h"
 /* RPW - End */