adopt version handling and output to transition from SVN to GIT (from compat)
pywikibot/version.py sync-ed with compat again

Change-Id: I54977388743f6b135ad296a3e3a46e1e519e81b2
Merge "adopt version handling and output to transition from SVN to GIT (from compat) pywikibot/version.py sync-ed with compat again"