Doodle improvements 2 (#176)

* Fix some doodle bugs and added Background color functionality

* added protections against accidental doodle erase, screen size changing

* resolve react warning about 'selected' on <option>

app/javascript/mastodon/features/compose/containers/doodle_button_container.js

@@ -8,7 +8,7 @@ const mapStateToProps = state => ({
 
 const mapDispatchToProps = dispatch => ({
   onOpenCanvas () {
-    dispatch(openModal('DOODLE', {}));
+    dispatch(openModal('DOODLE', { noEsc: true }));
   },
 });