Added some terrain tests, and found a fun race condition in the sqlite

terrain driver in the process, which is now fixed.  yay for unit tests!

OpenSim/Data/SQLite/Tests/SQLiteRegionTest.cs

@@ -55,7 +55,7 @@ namespace OpenSim.Data.SQLite.Tests
         [TestFixtureTearDown]
         public void Cleanup()
         {
-            System.IO.File.Delete(file);
+            // System.IO.File.Delete(file);
         }
     }
 }