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_euler.py

@@ -0,0 +1,3 @@
+import Mathutils
+
+# todo