I got tired of drive-by spelling fixes, so I figured I'd just take care of them all at once.
This only corrects errors in the dartdocs, not regular comments, and I skipped any sample code in the dartdocs. It doesn't touch any identifiers in the dartdocs either. No code changes, just comments.
* first pass
* improvements
* extract terminal.dart
* rebase
* add default terminal to context
* The analyzer wants the ../ imports in front of the ./ imports
* review notes