rupa's TADA68 layout

i've swapped the lufa-ms bootloader for caterina

most everything is in my userspace

• win/alt -> alt/cmd
• alt/fn -> fn/alt
• grave escape, with alt override
• caps is another fn key, CAPS on fn-rctl

fn layer:

• no wasd arrows
• rotate mute/vol
• backlight -> breathing, step, toggle
• swap home and ins
• unicode chars and strings sprinkled around
• script modes!
• (one-shot) right versions of shift/ctl/alt/gui (not working quite right yet)