Implement RFC 157

[jng]

​https://trac.osgeo.org/mapguide/wiki/MapGuideRfc157

[jng]

In 9143:

Implement RFC 157

This adds a new overload of MgMap::Create that accepts:

• map definition id
• map name
• image width
• image height
• view center X
• view center Y
• view scale
• dpi

With this overload, the created MgMap instance can be used on the following APIs statelessly without needing to open it first from a session repository (via a session id and map name pair)

• MgRenderingService::QueryFeatures
• MgRenderingService::QueryFeatureProperties
• MgRenderingService::RenderMapLegend
• MgRenderingService::RenderDynamicOverlay

With this change, there is enough APIs in place from which to build a stateless map viewer that can perform selections and does not require creating or interacting with a session repository or resources inside it.

As an addendum to the original RFC, the MgSelectionBase::SetMap method has also been promoted to EXTERNAL_API to allow selections from an MgFeatureInformation to be interrogated without throwing.

A server unit test has been added to verify these new MgMap::Create parameters stick on the map.

A series of .net unit tests have been added to exercise the aforementioned rendering service APIs using the statelessly-created MgMap.

Fixes #2766

[jng]

Milestone renamed