* Committing what I have on the BulletDotNETPlugin that I have so far.

* It's not ready to try.   It doesn't do what you expect in many ways.
* It throws errors and prints jibberish on the console
* Test it out only if you're brave and you've backed up first.
* The opensim.ini line is physics = BulletDotNETPlugin

OpenSim/Region/Physics/BulletDotNETPlugin/BulletDotNETPluginStructs.cs

@@ -0,0 +1,33 @@
+using System;
+
+public enum StatusIndicators : int
+{
+    Generic = 0,
+    Start = 1,
+    End = 2
+}
+
+public struct sCollisionData
+{
+    public uint ColliderLocalId;
+    public uint CollidedWithLocalId;
+    public int NumberOfCollisions;
+    public int CollisionType;
+    public int StatusIndicator;
+    public int lastframe;
+}
+
+[Flags]
+public enum CollisionCategories : int
+{
+    Disabled = 0,
+    Geom = 0x00000001,
+    Body = 0x00000002,
+    Space = 0x00000004,
+    Character = 0x00000008,
+    Land = 0x00000010,
+    Water = 0x00000020,
+    Wind = 0x00000040,
+    Sensor = 0x00000080,
+    Selected = 0x00000100
+}