tgstation-server DMAPI v7.0.0

Full changelog can be found here.

• Various event names changed to be engine agnostic. (#1666 @Cyberboss)
• Corrected documentation that stated a /datum/tgs_version engine version would be returned to properly say they will be stringified. (#1666 @Cyberboss)
• Added enums and function for retrieving the current engine version. (#1666 @Cyberboss)
  #tgs-dmapi-release