Add Microlite20 Character Sheet

This adds in a simple Microlite20 character sheet.

Potential issues (I am not a "mentor"-level subscriber and haven't been able to test this template):

- Documentation is unclear if we _have_ to prefix all CSS classes with 'sheet-' or if that is "automagically" done.

- Documentation is also unclear if we _have_ to namespace all classes within 'charsheet' or if that is also "automagically" added for us.