[sharedmemory] Fill-out calculateJacobian command.

The server command processor actually didn't do anything with
the local point that was passed along with the calculateJacobian
command. Added in the necessary bit of math to return the
corresponding jacobian.

Also, fixed a typo in pybullet that was returning the same
jacobian for translation and rotation.

src/BulletInverseDynamics/IDMath.cpp

@@ -33,6 +33,18 @@ void setZero(mat33 &m) {
 	m(2, 2) = 0;
 }
 
+void skew(vec3& v, mat33* result) {
+	(*result)(0, 0) = 0.0;
+	(*result)(0, 1) = -v(2);
+	(*result)(0, 2) = v(1);
+	(*result)(1, 0) = v(2);
+	(*result)(1, 1) = 0.0;
+	(*result)(1, 2) = -v(0);
+	(*result)(2, 0) = -v(1);
+	(*result)(2, 1) = v(0);
+	(*result)(2, 2) = 0.0;
+}
+
 idScalar maxAbs(const vecx &v) {
 	idScalar result = 0.0;
 	for (int i = 0; i < v.size(); i++) {

src/BulletInverseDynamics/IDMath.hpp

@@ -12,7 +12,8 @@ void setZero(vec3& v);
 void setZero(vecx& v);
 /// set all elements to zero
 void setZero(mat33& m);
-
+/// create a skew symmetric matrix from a vector (useful for cross product abstraction, e.g. v x a = V * a)
+void skew(vec3& v, mat33* result);
 /// return maximum absolute value
 idScalar maxAbs(const vecx& v);
 #ifndef ID_LINEAR_MATH_USE_EIGEN