Avoid colliding with AvoidNodes

These are placed under the RootCollisionNode hierarchy, but the shapes they
hold aren't collided with. Their exact function is unknown, but seems to be
related to lava? Maybe damage avoidance info for the AI.

components/nif/niffile.cpp

@@ -207,7 +207,7 @@ struct RecordFactoryEntry {
 static const RecordFactoryEntry recordFactories [] = {
 
     { "NiNode",                     &construct <NiNode                      >, RC_NiNode                        },
-    { "AvoidNode",                  &construct <NiNode                      >, RC_NiNode                        },
+    { "AvoidNode",                  &construct <NiNode                      >, RC_AvoidNode                     },
     { "NiBSParticleNode",           &construct <NiNode                      >, RC_NiBSParticleNode              },
     { "NiBSAnimationNode",          &construct <NiNode                      >, RC_NiBSAnimationNode             },
     { "NiBillboardNode",            &construct <NiNode                      >, RC_NiNode                        },

components/nif/record.hpp

@@ -36,6 +36,7 @@ enum RecordType
 {
   RC_MISSING = 0,
   RC_NiNode,
+  RC_AvoidNode,
   RC_NiTriShape,
   RC_NiRotatingParticles,
   RC_NiAutoNormalParticles,

components/nifbullet/bulletnifloader.cpp

@@ -185,6 +185,10 @@ void ManualBulletShapeLoader::handleNode(btTriangleMesh* mesh, const Nif::Node *
     else
         isCollisionNode = isCollisionNode && (node->recType != Nif::RC_RootCollisionNode);
 
+    // Don't collide with AvoidNode shapes
+    if(node->recType == Nif::RC_AvoidNode)
+        flags |= 0x800;
+
     // Marker objects
     /// \todo don't do this in the editor
     std::string nodename = node->name;