Possibly contentious space in 'upper case' and 'lower case'
Assorted typos and capitalization
Dang apostrophes (and other punctuation)
Think of the children
Contentious: center vs centre
Punctuation/style fixes. PEP8-compliant comments in examples.
Merge branch master of https://github.com/vhata/umonya_notes into vhata-master

Conflicts:
  files.html
  program_state.html