Fixes #22

Each (dfu) interface may have more than one a ltsetting each with their own index and name. According to the DFU_1.1 pdf section 4.2.3, "* Alternate settings can be used by an application to access additional memory segments. In this case,
it is suggested that each alternate setting employ a string descriptor to indicate the target memory
segment; e.g., 'EEPROM'." Whether or not we end up using multiple memory segments it is still good to have a descriptive name incase there are other dfu devices connected.

Edit: Fixed previous indentation

- Heavily modified, not compatible with McHCK images
- Uses 4k of Flash (rather than 3k)
- LED turns on when in firmware flash mode
- Changed the USB IDs
- Added CMake build system
- Updated linker script to be closer to what is used for the rest of the projects
- Removed a lot of unnecessary code
- Added a license header to each file (using the same license as the McHCK had)
- Updated the USB Vendor, Product and Serial strings
- Using the Kiibohd initialization sequence rather than the McHCK one
- Using Kiibohd interrupt vector table and other misc mk20dx setup