[FIX] fixed error handling for integration
[TESTS] added tests for actions in TableExplorerModel.py
[CLEANUP] better exception handling qt in event handler
[FIX] TableExplorer: fixed missing repaint when undo/redo of cell values
[FIX] fixed some param types for failed integration
[FIX] fixed accidentally modification of input tables in ms.mergeTables
[FEATURE] more consinstent handling for agg on emtpy column