Get rid of the abstract forms

Visual Studio has a serious limitation with Form and Control
inheritance, and not even a custom TypeDescriptorProvider seems to help,
so for now just work around the limitation with non abstract classes.
Updated German language file - thx Siegwarth Binger :)
fr-FR translation: restore damage
fr-FR translation: s/deux points/un deux-points/
fr-FR translation: consistently use thin space before [:;!?]