some rudimentary work in order to pass the selected GUIListItem to the context item addon
Removed deprecation warning of unused include...

removed a duplicate //TODO:

removed an unnessesary //TODO:
The translatable labels are now stored in .po files instead of the addon.xml
Moved the creation of the addonc context items out of GUIMediaWindow into subclasses (prevents them from showing up in the middle)
Context Item Addons possible in Login Screen