Raptors Return -- quake.zone browser build

Repacked for browser play from:
  http://www.quaketerminus.com/mods/pcrr.zip

Only runtime files are included in the game package; the original documentation
is reproduced below. All rights remain with the original authors.
Runs on LibreQuake (../../librequake/NOTICES.txt) and FTEQW (GPL-2.0, ../../licenses/gpl-2.0.txt).

(The original archive contained no readme.)