Added new class for checking requested map size and layer count
Added tests for GetMapLimitChecker
Integrated GetMapLimitChecker with WMSController. Added export of LayerLimit, MaxWidth and MaxHeight to WMS 1.3.0 capabilities.
Handbook: Added new WMS config parameter description
Merge pull request #321 from occamlabs/3.3-feature-limit-wms-map-size

WMS: Add options for limiting map size and number of layers