Thank you kindly, Tlaukkan (Tommil) for a patch that:

Fixed all NHibernate unit tests by implementing missing persistency 
methods, tables, columns and fixing bugs in the existing implementation.
Two minor changes to classes outside NHibernate module: Added Scene 
instantiation for SceneObjectGroup in OpenSim.Data.Tests.BasicRegionTest 
as this was required by the NHibernate persistency. In the process added 
also mock constructor to Scene which only populates RegionInfo in the scene 
which is used by ScenePart.RegionUUID. NHibernate module is still in 
experimental state and has not been tested at opensim region or ugaim runtime 
configuration. Adding unit tests to build is not yet advisable nor using 
NHibernate module in any production setup.

1 files changed, 1 insertions, 0 deletions

diff --git a/prebuild.xml b/prebuild.xml
index c4be734..64c9588 100644
--- a/prebuild.xml
+++ b/prebuild.xml
@@ -1588,6 +1588,7 @@
       <Reference name="System" localCopy="false"/>
       <Reference name="System.Xml"/>
       <Reference name="System.Data"/>
+      <Reference name="System.Drawing"/>
       <Reference name="OpenSim.Data"/>
       <Reference name="OpenSim.Framework"/>
       <Reference name="OpenSim.Framework.Console"/>