Close #206: greytrack_font_rotation is linear only
Remove accidentally committed file

Note this checked in file had an unfortunate typo, XY vs XZ,
and for more background on random access to blocked XZ format
see my blog post here:
http://blastedbio.blogspot.co.uk/2013/04/random-access-to-blocked-xz-format-bxzf.html

See also my backport of the lzma module which this used,
https://github.com/peterjc/backports.lzma
http://pypi.python.org/pypi/backports.lzma/