SelectCRSDialog: remember last selection (in running instance)

refs #639

Change-Id: If000cf90ab231b4954b6d19e12c4f85166e07478
Reviewed-on: http://gerrit.esdi-community.eu/3101
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>