Started clean with copies of all files, re-forked. Retained copyright notices in both my changed .rb files - su_shapes.rb, su_shapes.rb/shapes.rb but deleted all original SU code.

Copied my changed code below copyright notices in these two files, saved, then committed.
Started clean with copies of all files, re-forked. Retained copyright notices in both my changed .rb files - su_shapes.rb, su_shapes.rb/shapes.rb but deleted all original SU code.

Copied my changed code below copyright notices in these two files, saved, then committed.
Removed change log to new file change.log (but can't see how to add file to tracked files in SourceTree)
Replaced single quotes by double quotes in shapes.rb  and su_shapes.rb
May have committed and pushed before saving latest changes so redoing last commit and push.
Found that .log files were in global Ignore list, removed that extension from list, and committed change.log.
change.log renamed to changelog.md
Merge pull request #6 from johnwmcc/master

Third attempt to push my changes