Live configuration updates

[HunterZ]

As restarting a server takes a long time, it's not always convenient that RLS shuts down the server whenever RLS itself needs to be restarted in order to pick up a config change.

I can think of a couple of approaches to deal with this:

• support having RLS take ownership of an already-running server process
  • most C++ process management frameworks don't support this
• support some kind of config file reload stimulus + logic
  • admin-only chat command?
  • config file change monitoring?

Note that both of these may require sending RCON commands or even restarting the server in order to apply changes. It may also be desirable/necessary to compare current config with updated config file to determine which actions need to be taken.

Restarts should probably be avoided - maybe just document and/or log what can't be applied until next server restart, and apply it next time that happens for any reason? This may require being able to queue application of config changes, so that RLS doesn't accidentally use new settings too early internally.