Fix colemak layout

The purpose of a keymap is NOT to define hint preferences for Ctrl, Shift, Alt, Esc, and other modifier keys. X11 has its own subsystem for that. For instance, to swap Caps and Ctrl, one can:

setxkbmap us colemak -option ctrl:swapcaps

Such preferences are not shared by users (e.g. Vim users and Emacs users), and even make the default remapping subsystem broken (e.g. swapping ctrl and caps using the previous command will make the old caps act as ctrl AND backspace simultaneously).

To illustrate the problem, imagine if the line removed in this commit was applied to the default us layout. It's that bad.