util/stats/barchart.py:
- there is no self.inner_axes
- don't append an empty value to self.xsubticks, otherwise
subsequent calls will get extra empty ticks
- rotate labels 30 degrees instead of 90 so it looks better
--HG--
extra : convert_revision : 1cbac6d1f92bfc6b2c1e886ad5f9d4c78a2b3820