cbbrowne custom keyboard

Due to cbbrowne@acm.org Christopher Browne

This was originally based on the default keyboard map, but I have been doing sundry experimentation:

To figure things out about the toolset
I'm an Emacs guy, so will be needing a fair bit of tuning
It made sense to mess around some with keyboard maps.
- I added Workman alongside Dvorak and Colemak
  - Boy, oh boy, these don't help
  - I have done 30 years of learning of Emacs key mappings, and these alternative keyboards massively mess me up
- I added a keypad, originally based on keymaps/numpad.c, but mighty substantially revised, as that one seems to be rotated 90 degrees from usual conventions for number pads