clear files table when deleting collection

gui/griffon-app/controllers/com/muwire/gui/CollectionsToolController.groovy

@@ -30,6 +30,7 @@ class CollectionsToolController {
         model.eventBus.publish(e)
         model.collections.remove(row)
         view.collectionsTable.model.fireTableDataChanged()
+        view.clearFilesTable()
     }
     
     @ControllerAction

gui/griffon-app/views/com/muwire/gui/CollectionsToolView.groovy

@@ -108,6 +108,11 @@ class CollectionsToolView {
         selectedRow
     }
     
+    void clearFilesTable() {
+        model.files.clear()
+        filesTable.model.fireTableDataChanged()
+    }
+    
     void mvcGroupInit(Map<String,String> args) {
         def centerRenderer = new DefaultTableCellRenderer()
         centerRenderer.setHorizontalAlignment(JLabel.CENTER)