Feature Description: Suggest ability to apply/override world visibilitylimits, hiddenlimits, and center on individual maps.

• Additional context: My base is predominantly underground (on the overworld), so I determined the x/z min/max and the y-level of my ceiling, and tried adding restrictions to additional maps (so I could have an underground view of just my base). Was able to specify custom perspective just fine for the Y-value cutoff, but the maps render the entire underground. I don't want all of the underground visible, since that may reveal resources and other structures to other players, but I also do not want to apply visibilitylimits to the entire overworld, just the underground perspective. (I doubt this suggestion will make it to the version of dynmap I'm using [Dynmap-2.6-beta-1-forge-1.7.10.jar], but it seems like it'd be a useful feature ongoing.)

Duplicate of #2926