Removed leftmost and rightmost columns and added a little more line drawing.

Trying to make a cycle of base layouts that can be chosen in sequence:
Hands Down Neu, Hands Down Gold, Dvorak, Colemak-DH, QWERTY, Canary
Ortho, Sturdy. Also replaced "lower" and "raise" layers with symbol
layer (inspired by Pascal Getreuer), navigation layer, and a numpad
layer with F-keys.

Though I do not understand why they are required nor what they mean.

All layouts should now have escape and tab on them, and to get
backspace on Hands Down Gold there are escape, backspace, and tab on
the nav layer now. I imitated the technique described in
zmkfirmware/zmk#1299 (comment)
to use conditional layers for num-lock.

No idea how that Z got in there.

Also updated copyright statement and added a to-do list.