Use Bidi Mirroring

Use the [Bidi Mirroring](http://www.unicode.org/Public/UNIDATA/BidiMirroring.txt) file instead of my old [openClosedUniGenerator.py](https://github.com/robotools/defcon/blob/master/tools/openClosedUniGenerator.py) for the open/close methods in `font.unicodeData`. Maybe add a new method called `mirroredRelativeForGlyphName`.