Added some items to TODO list.

TODO.txt

@@ -2,7 +2,12 @@ Code:
 - Connect to VTK.
 - Rotation has a 'bump' at angle = 0.
 - Try to get rid of relative imports.
+- Widget offset/position methods.
 
-Thesis:
+Tests:
+- Nested widgets.
+- Draggable shapes.
+
+Report:
 - Network protocol.
 - Cited to VTK book, is this ok if I didn't read it?