This PR adds a new utility mechanic for the cult. Pylons can now be upgraded into arcane defensive turrets, which fire bolts of demonic energy. These turrets are entirely automated, somewhat-rapid firing, extremely accurate and quite long ranged, but their damage is very low, and thus their total DPS, even with the fire rate, is still far lower than most real ranged weapons.
Adds Shells. Adds tags. Adds IPC subspecies. Adds HK-47's. Does not add IPC construction.
Beyond the obvious review of shells, the exact stats of the IPC subspecies need review. They were largely an afterthought, and quickly overshadowed by the shell project.
