Merge image related changes from the render branch. This includes the image

tile cache code in imbuf, but it is not hooked up to the render engine.


Imbuf module: some small refactoring and removing a lot of unused or old code
(about 6.5k lines).

* Added a ImFileType struct with callbacks to make adding an file format type,
  or making changes to the API easier.
* Move imbuf init/exit code into IMB_init()/IMB_exit() functions.
* Increased mipmap levels from 10 to 20, you run into this limit already with
  a 2k image.
* Removed hamx, amiga, anim5 format support.
* Removed colormap saving, only simple colormap code now for reading tga.
* Removed gen_dynlibtiff.py, editing this is almost as much work as just
  editing the code directly.
* Functions removed that were only used for sequencer plugin API:
  IMB_anim_nextpic, IMB_clever_double, IMB_antialias, IMB_gamwarp,
  IMB_scalefieldImBuf, IMB_scalefastfieldImBuf, IMB_onethird, IMB_halflace,
  IMB_dit0, IMB_dit2, IMB_cspace
* Write metadata info into OpenEXR images. Can be viewed with the command
  line utility 'exrheader'

For the image tile cache code, see this page:
http://wiki.blender.org/index.php/Dev:2.5/Source/Imaging/ImageTileCache

source/blender/imbuf/intern/dds/dds_api.cpp

@@ -31,13 +31,12 @@
 extern "C" {
 
 #include "imbuf.h"
-#include "imbuf_patch.h"
 #include "IMB_imbuf_types.h"
 #include "IMB_imbuf.h"
 #include "IMB_allocimbuf.h"
 
 
-short imb_save_dds(struct ImBuf * ibuf, char *name, int flags)
+int imb_save_dds(struct ImBuf * ibuf, char *name, int flags)
 {
 	return(0); /* todo: finish this function */
 
@@ -78,6 +77,9 @@ struct ImBuf *imb_load_dds(unsigned char *mem, int size, int flags)
 	Color32 pixel;
 	Color32 *pixels = 0;
 
+	if(!imb_is_a_dds(mem))
+		return (0);
+
 	/* check if DDS is valid and supported */
 	if (!dds.isValid()) {
 		/* no need to print error here, just testing if it is a DDS */