More GJK degeneracy fixes, thanks Jacob Langford for the feedback:

http://code.google.com/p/bullet/issues/detail?id=250

Added missing files for Maya Dynamica plugin
Thanks Herbert Law for the patch, and damrit and others for the report
http://code.google.com/p/bullet/issues/detail?id=231

Fix btQuaternion shortestArcQuat, thanks Stan Melax for original fix and shogun for reminder
http://bulletphysics.com/Bullet/phpBB3/viewtopic.php?f=9&t=1989

Implemented btDiscreteDynamicsWorld::removeCollisionObject (and btSoftBodyDynamicsWorld) to avoid
crashes. Thanks Jacob Langford for bringing that up.

Minor sphere-debug drawing issue (spheres were drawn inside-out (wrong face winding)

src/LinearMath/btVector3.h

@@ -635,4 +635,24 @@ SIMD_FORCE_INLINE void	btUnSwapVector3Endian(btVector3& vector)
 	vector = swappedVec;
 }
 
+SIMD_FORCE_INLINE void btPlaneSpace1 (const btVector3& n, btVector3& p, btVector3& q)
+{
+  if (btFabs(n.z()) > SIMDSQRT12) {
+    // choose p in y-z plane
+    btScalar a = n[1]*n[1] + n[2]*n[2];
+    btScalar k = btRecipSqrt (a);
+    p.setValue(0,-n[2]*k,n[1]*k);
+    // set q = n x p
+    q.setValue(a*k,-n[0]*p[2],n[0]*p[1]);
+  }
+  else {
+    // choose p in x-y plane
+    btScalar a = n.x()*n.x() + n.y()*n.y();
+    btScalar k = btRecipSqrt (a);
+    p.setValue(-n.y()*k,n.x()*k,0);
+    // set q = n x p
+    q.setValue(-n.z()*p.y(),n.z()*p.x(),a*k);
+  }
+}
+
 #endif //SIMD__VECTOR3_H