Added baking for softbodies.

Works as follows;
- press the 'show bake settings' button (no space left... :)
- define start/end frame for bake, and an interval step.
  The baked result interpolates nicely (Bspline, 4 keys) so in general a
  step size of 2 or 3 still gives OK results.
- Press "BAKE". This will do a full animation + playback. Press ESC if it
  you don't want it.

Once Baked, the BAKE button becomes a FREE BAKE. As reminder the softbody
buttons get blocked with error() menu.

This saves OK in a file. Renders any frame, including fields and moblur.
You can also set a "Timeoffs" for the softbody. And yes, this should be
in the NLA once... :)

NOTE! With this commit, files saved with the old (first commit) version by
Jens Ole won't read the settings back... he stored all sofbody variables in
Object, which was moved to a new struct when I did my first commit on SB
(over a month ago)

Also note that I moved particle deflecting & softbody to a new include.

source/blender/src/drawobject.c

@@ -58,6 +58,7 @@
 #include "DNA_meshdata_types.h"
 #include "DNA_meta_types.h"
 #include "DNA_object_types.h"
+#include "DNA_object_force.h"
 #include "DNA_space_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_screen_types.h"