* Better module import error handling
* Allow co-installation of Python2 and Python3 version of FreeCAD
* Add FreeCAD.Logger class for convenient logging in Python. See class
document for more details.
(this mostly aims at new modules and extension modules which want to use pip)
- any module having problems with nameclashes can use this syntax (from freecad import module)
- current imports still work (backward cobatibility)
- python extension moduels can be installed (pip) to python std path (eg.: site-packages)
- adding app, gui to the new freecad package:
```
from freecad import app
from freecad import gui
```
- syntax for importing c++ extension will not change
```
import FreeCAD as App
import FreeCADGui as Gui
```
This commit adds a attribute __cmake__ to App which is a list holding all compile time cmake variables starting with BUILD.
Only export BUILD variables