Mathutils doc improvements + other small things

- bpy.app moved into PyStructSequence (used by sys.float_info)
- added buildinfo into bpy.app.build_*
- bpy.ui removed (wasnt used)
- include external example files in Mathutils docs (only Mathutils and Vector are currently written)
- added support to auto document PyStructSequence's
- CMake had "'s inside all its strings.

source/blender/python/doc/examples/mathutils.py

@@ -0,0 +1,17 @@
+import Mathutils
+
+vec = Mathutils.Vector(1.0, 2.0, 3.0)
+
+mat_rot = Mathutils.RotationMatrix(90, 4, 'X')
+mat_trans = Mathutils.TranslationMatrix(vec)
+
+mat = mat_trans * mat_rot
+mat.invert()
+
+mat3 = mat.rotation_part()
+quat1 = mat.to_quat()
+quat2 = mat3.to_quat()
+
+angle = quat1.difference(quat2)
+
+print(angle)