Brush flip/rotate functions ineffective on diagonal/straight line presets

```
Since diagonal and straight-line brushes are trivially flippable (in theory; 
just change the brush type) and rotatable, the rotate and flip functions should 
work for these brush types. Currently they do nothing.


```

Original issue reported on code.google.com by `fintic...@gmail.com` on 17 Oct 2013 at 12:26
