Fixed: Transaction edits not persisted to db. Fixes #180

Fixed: Fatal crash when error occurs in importing/exporting transaction (instead of displaying error message)
Fixed: Editing a transfer transaction does not edit other side of the transaction
Removed progress dialog from database migration (seems to be cause of some crashes)
Transaction templates are not only available when creating new transactions
Added some input validation to database adapters
Update German translation
Merge remote-tracking branch 'upstream/develop' into develop