update .gitignore
xform -> transform
move to_s methods, add whitespace
pppts now allows 'debug' switch & e.g. '+200' to run tests 200..
work on to_s memoization
fix to_s memoization spacing issues
reposition str0, str1 methods
indented -> indent (and incorporate old indent method)
new class List provides list_str str0 default for many classes
tabs -> spaces, rm trailing whitespace
ostruct -> hash for conf
uncomment harmless continuation-line check code