Implementation of interface (template) for all modules

- Correct setup of logging
- all inkycal-modules inherit from the given template
- Added basic, optional validation
- more code cleanups
- fixed a few minor bugs

inkycal/__init__.py

@@ -1 +1,5 @@
-from .Inkycal import inkycal
+from inkycal.modules.inkycal_agenda import agenda
+from inkycal.modules.inkycal_calendar import calendar
+from inkycal.modules.inkycal_weather import weather
+from inkycal.modules.inkycal_rss import rss
+