Form support in the slides

This will allow us to present interactive quizzes after topics to gauge
immediate student comprehension. We can quiz towards the end to gauge
retention as well.

This will also allow us to collect survey data directly, making us
Internet independent.

Features:

- Create HTML forms using custom markdown syntax
    - Can specify machine parsable keys & human readable labels
    - Supports radio/checkbox/select/text/textarea
    - Specify defaults for radio/checkbox/select
    - Radio/checkboxes specified on multiple lines become list items
    - Selects can be specified on multiple lines for readability.
- Keys responses by IP address to eliminate duplication
- Students can resubmit if they change responses
- Markup to provide instructor with live reporting of responses
- Button to display results on projector (static only for now)
- All form responses saved in existing metadata uploaded by classroom
  automation tools.

TODO:

- Documentation.
- Clean up presentation. A lot.
- Form validation for required elements.
- Track down and fix the sneaky crasher that seems to be showing up more
  often now.
- More testing.