Bump version number to 2.1-SNAPSHOT
Adapt to core's new PRE_SEND hook.
Adapt to DeepaMehta 4.0.13-SNAPSHOT
Support for multi-facets.

Facets can be defined with cardinality "Many".

In conjunction with the optional Checkbox Renderer this allows the
categorization of Geo Objects via multiple-selectable category systems.
Fix access control.

The Kiezatlas topic types get Access Control information.
2.1 Release.

Update version number and README.
Merge tag '2.1'

Source Code