'mitre' typo causes exception on saving
*Created originally on Bitbucket by [n23 (TC)](https://bitbucket.org/%7B82dc7bbd-6dce-4d32-8416-f343f0566710%7D/)*
Message: *AttributeError: 'bool' object has no attribute 'to_tree'*
../drawing/line.py:128
../drawing/line.py:162
Note last one must be changed from 'self.mitre = bevel' to 'self.miter = miter' or it won't work
issue