remove Canvas model, not exposed on python side
remove old and no-longer existent DataRangeBoxSelectTool
remove unused cont_ranges and discrete_ranges
remove old and unused properties on glyphs
update glyph tests
remove glyph cruft from JS side too
remove ignored radius_units from glyphs.py example
do need units defaults for cicle, however
Merge pull request #1591 from bokeh/task/1583_unused_properties

Clean up unused properties