To make keymaps look nicer, easier to read, introduce the `___` and `XXX`
aliases. The former is an alias to `Key_Transparent`, the latter to `Key_NoKey`.
The `genetare_keymaps.pl` tool was updated to support these, too, with the
additional functionality, that all strings that are made up entirely of
underscore or Xes, and are two or more characters long, will be treated as
`___`/`XXX`, respectively. This makes it possible to space keys in a nicer way
in the source layout files.
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>