Aligns *.h and *.c to underscore naming convention.
These were kept (with warnings) for backwards compatibility with external boards/shields:
- kscan-mock.h
- matrix-transform.h
They should be removed in the future.
PR: #523
Added some utility functions and an event for tracking the state of the
USB connection.
Updated endpoints.c to select a single endpoint to send HID reports to
based on the status of the USB and BLE connections. Partially fixes#206.
Future commits will add a user setting to control which endpoint is used if
both USB and BLE are ready.