Documentation: Improved Amethyst markup in command/variable docs

Whitespace only acts as a separator in Amethyst; replaced the
now-meaningless newline escape chars with a custom macro
(cbr = console break).
Documentation: Script for generating wiki pages for commands/variables

Expected to be run in "doomsday/doc".
Merge branch 'master' of ssh://github.com/skyjake/Doomsday-Engine