No combat allowed until a specific time

It would be good if there was an optional configuration setting which prevented violence until a certain time (UTC). This would allow players to get set up before the game began properly.

No files or tests are named. Start by locating the configuration system and the combat or violence handling, then determine how the UTC start time is represented and tested; done means the optional setting prevents violence before the configured time while preserving current behavior when unset.

Written by the indexing model from the issue text.