Rework of the motion model, to make it more explcit.
Update docstrings, small enhancements to Oskar's motion rework.
Merge pull request #692 from ostcar/motion_rework

motion rework
Add --no-run parameter

This parameter allows e.g. to synchronize the database without starting
the webserver.
Add command to backup the database
Add a simple wxPython based gui frontend for openslides
Update portable to use new gui frontend

 - switch portable to use gui frontend

 - add version resource and icon to portable

 - Regenerate openslides.exe