added monster spawns

removed extra character from 2 mapgen arrays

Removed extra character from 2 buildings' mapgen arrays: cs_car_showroom and ws_regional_dump (no. 15/16).

Thanks to Zhilkin for pointing this out.

changing om_terrain IDs

matching "om_terrain" IDs in the building files to those within "overmap_terrain"

Update gardening_allotment.json