First pass at data structure editor

Add an "edit" button to collection views. Users can edit and save EDN
and the underlying datastructures will be updated.

I had to be careful with the save process because

(om/update! data new-data)

triggers a re-mount of the component, which caused an error when we
tried to set state on the newly unmounted component.
Update gitignore
Support printing dates
Formatting, comment fix
Support doubleclicking on datastructures to edit them
Updates from https://github.com/noprompt/ankha/pull/8

- focus editor on edit, save on blur
- copy tweaks
- predicates to make key detection read better
- code formatting tweaks
Remove debugging class
Merge pull request #8 from travis/editing

Allow users to edit datastructures