Camera tracking: support of tripod motion solving

Expose option into interface to use modal solver which currently
supports only tripod motion.

This solver requires two tracks at least to reconstruct motion.
Using more tracks aren't improving solution in general, just adds
instability into solution and slows down things a lot.

Refirement of camera intrinsics was disabled due to it's not only
refines camera intrinsics but also adjusts camera position which
isn't necessary here

To use this solver just activate "Tripod Motion" checkbox in
solver panel.

Merged from tomato: svn merge ^/branches/soc-2011-tomato -r45622:45624 -r46036:46037

P.S. Quite experimental yet, requires more checking and probably
tweaks to prevent camera jumps when tracks apperars/disappears
from the screen.

release/scripts/startup/bl_ui/space_clip.py

@@ -227,12 +227,16 @@ class CLIP_PT_tools_solve(Panel):
                      else "Object Motion")
         col.operator("clip.clear_solution")
 
+        col = layout.column()
+        col.prop(settings, "use_tripod_solver")
+
         col = layout.column(align=True)
+        col.active = not settings.use_tripod_solver
         col.prop(settings, "keyframe_a")
         col.prop(settings, "keyframe_b")
 
         col = layout.column(align=True)
-        col.active = tracking_object.is_camera
+        col.active = tracking_object.is_camera and not settings.use_tripod_solver
         col.label(text="Refine:")
         col.prop(settings, "refine_intrinsics", text="")