- Remove the concept of "mcus". With only one target platform
(CircuitPython), it no longer makes a bunch of sense and has been kept
around for "what if" reasons, complicating our import chains and eating
up RAM for pointless subclasses. If you're a `board`, you derive from
`KeyboardConfig`. If you're a handwire, the user will derive from
`KeyboardConfig`. The end. As part of this, `kmk.hid` was refactored
heavily to emphasize that CircuitPython is our only supported HID stack,
with stubs for future HID implementations (`USB_HID` becomes
`AbstractHID`, probably only usable for testing purposes,
`CircuitPython_USB_HID` becomes `USBHID`, and `BLEHID` is added with an
immediate `NotImplementedError` on instantiation)
- `KeyboardConfig` can now take a HID type at runtime. The NRF52840
boards will happily run in either configuration once CircuitPython
support is in place, and a completely separate `mcu` subclass for each
mode made no sense. This also potentially allows runtime *swaps* of HID
driver down the line, but no code has been added to this effect. The
default, and only functional value, for this is `HIDModes.USB`
- Most consts have been moved to more logical homes - often, the main
or, often only, component that uses them. `DiodeOrientation` moved to
`kmk.matrix`, and anything HID-related moved to `kmk.hid`
The thumb cluster maps a little goofy and I'd like to clean up the
keymap here - it's ENTIRELY NOT OBVIOUS how this works right now. Using
this keymap as an example, the physical layout of my thumb cluster is
actually:
Far left: Left
Next to the right: Right
Bottom right: Shift
Top right: MO(2)
You can see what this maps to in code, and it's not at all intuitive.
`swap_indicies`, which we already support, is useless here because,
unlike the Planck/Klaranck, these aren't 1:1 key swaps, but an entirely
custom mapping of columns. This will require something like QMK's
solution to fully custom (or at least partially custom) keymaps at a
core level, and isn't something I feel like tackling tonight
necessarily.
This brings this naming into consistency with both fellow consts in the
same file (ex. LeaderMode is singular) as well as the variables in which
the consts are usually used (usually a `Firmware.unicode_mode` attribute
in a keymap).
