* Remove chording as it is not documented, not used, and needs work.
* Make Leader Key an optional feature.
* Switch from `PREVENT_STUCK_MODIFIERS` to `STRICT_LAYER_RELEASE`
* Remove `#define PREVENT_STUCK_MODIFIERS` from keymaps.
* Added Contra keyboard support
The configuration came from a source distribution of the firmware on the
Contra's official website.
I have also included a simple MIDI keymap. (And it works!)
* Changes to Contra config and README
* Readme has been changed as requested by jackhumbert
* Config has been changed to add the Cartel and Contra names to
the USB configuration.