Automatically calculate bounds for WMS

[zspitzer]

following up on ​http://www.nabble.com/WMS-GetCapabilities-td20519654.html

apparently MapGuide requires bounds to be defined for publishing via WMS.

When bounds aren't defined, these could be simply calculated (and cached)

see #768

[tomfukushima]

I remember asking for this when this feature was first developed. I believe the argument against doing this was that these values would get stale if the data was updated. Then of course, there was the issue of having enough time to do it in the first place.

[jbirch]

Removing version from enhancement request. If this enhancement request has been addressed or is no longer required, please close ticket.

[jng]

Client tools (ie. Maestro) can do this