Add "region get" command as a synononym for "show region" console command.

This matches existing similar commands and a soon to be added "region set" command.
Add "region set" console command.

This current allows one to set two region parameters
agent-limit <int> will set the current root agent limit for the region, as also settable through the viewer, though some impose a max setting (e.g. 100).
max-agent-limit <int> will set the maximum allowed root agent limit.  This can also be set via the MaxAgent parameter in region config.
Actually persist a changed console set agent-limit via "region set".

Unfortunately, it's not currently easy to do this with "max-agent-limit"
- this must be separately set as MaxAgents in region config if it's to persist over restarts.