Slightly refactored selection tool

Now the move tool doesn't depend on how the selection has been made anymore

js/tools/SelectionTool.js

@@ -2,4 +2,8 @@ class SelectionTool extends Tool {
     constructor(name, options, switchFunc) {
         super(name, options, switchFunc);
     }
+
+    cutSelection() {}
+    pasteSelection(){}
+    copySelection(){}
 }