[apps/editor_controller] Fix backspace handling in text area

The editor controller handles backspace if it is at the beginning of a
line, to remove multiple spaces to match the indentation, but it should
not do so if there is an ongoing selection

apps/code/editor_controller.cpp

@@ -77,7 +77,7 @@ bool EditorController::textAreaDidReceiveEvent(TextArea * textArea, Ion::Events:
     return true;
   }
 
-  if (event == Ion::Events::Backspace) {
+  if (event == Ion::Events::Backspace && textArea->selectionIsEmpty()) {
     /* If the cursor is on the left of the text of a line, backspace one
      * indentation space at a time. */
     const char * text = textArea->text();