lumps: Add demo1
lumps: Add demo1

New demo1 to replace the dummy one that was here.

Signed-off-by: Mike Swanson <517655fde76fa2f07143b6c6f1774e4fae45930a@gmail.com>

jmtd/freedoom,CWolfRU/freedoom,CWolfRU/freedoom,jmtd/freedoom,jmtd/freedoom