Clarified documentation.
Fixed circular imports with a hack.

I'll rework everything again, eventually.
Reimplemented the 'completions' command.
Aesthetic changes to the default template.
Fixed the 'edit' command.

The subprocess commands that return output are appropriate for executing a
child editor process. I added a flag to distinguish 'interactive' commands.
Aesthetics.
Fixed virtualenv sourcing.
Instructions for sourcing virtualenvs...

...automatically for new windows.