Drashna's ErgoDox EZ Underglow Mod

This is based on the default Ergodox EZ keymap.

This modifieds the keymay so that it uses the underglow to indicate which layer you're on, rather than the top LEDs.

Default colors are "teal" for base layer, "red" for Symbols, and "green" for mouse/media. Blue would be the next layer, if you had more.

Additionally, the top LEDs are Shift/Control/Alt indicators instead (in that order).