Removed all classes which no longer had any usage after the removal of
AMDataView, including:
- AMQueryTableModel
- AMSignallingGraphicsView
- SGMDataViewWithActionButtons
- AMDataView
- AMDataViewActionBar
- AMDataViewEmptyHeader
- AMDataViewSectionHeader
- AMDataViewWithActionButtons
- AMFlowGraphicsLayout

Altered:
- SGMAppController ~ No longer has include for
SGMDataViewWithActionButtons.
Merge pull request #838 from acquaman/Issue820

Pull request for Issue820: Cleaning up after replacement of AMDataView