MAPPING: add 4 drone mutations

Carrier - the orange, parasite-carrying drones from Tears for Tarnor:
Oasis Colony Spaceport
Red Giant - the large, red, high-health drones from Nest: Cave
Ghost - the nearly-invisible drones from BioGen Corporation: Invisible
Threat
Summoner - the glowing green drone that summons a horde from Tears for
Tarnor: Insertion Point

These drones are supported in spawners and as entities in hammer, and
are spawned by the director at the same rate as shieldbugs, parasites,
harvesters, and boomers.