start of checkerboard sprite refactor; checkerboard properties object
initial checkerboard sprite class with a refactored texture generator
removed non-checkerboard-specific properties
moved new checkerboard code into other files to stay inline with current abstraction style
factory method for creating checkerboard properties objects from json
msequence code converted to use checkerboard properties object
enforce colors to be tuples; missed renaming some variables
to be a checkerboard, we enforce at least 2x2 tiles
reversal requires we actually flip the colors