Add support for Dactyl Manuform 4x6

[genkobar]

I added support for my version of the Dactyl Manuform, which is a 4x6 configuration of Carbonfet's fork.

I haven't created a PR to QMK with my keyboard and a default keymap, should this PR wait until there's a default keymap available in QMK?

[yskoht]

@genkobar

Sorry for the late reply.

should this PR wait until there's a default keymap available in QMK?

keymapviz only supports QMK keyboard. So, I will merge this PR when your keyboard is available in QMK.

If your keyboard will not be available for QMK, we may need to consider a feature to make it easier to set up your own keyboard in keymapviz without the PR.

[genkobar]

keymapviz only supports QMK keyboard. So, I will merge this PR when your keyboard is available in QMK.

All right, that sounds good :)

I'm finalizing my PR to QMK, so I believe it will be available in QMK eventually.