#227 RendererTools: created the methods showErrorState() and showNormalState()
#227 Sb_StadtbildWindowSearch: added item state changed listener to cboStreet and cboOrt. If some invalid element is selected then they will be painted accordingly
#227 RendererTools.changeOnlyEditorBackgroundAndForegroundColorOfEditableJComboBox() look for any JButton and set its color back
#227 added dialogs if search should be executed but the ort or strasse is invalid
Merge branch 'feature/227-Stadtbildserien-Search-accepts-non-existing-streets-and-places' into dev