Changes

To VobCoorder, add:

/** Create a new coordsys whose transformation 
 * is the concatenation of the parent and child 
 * transformations: x' = parent(child(x))
 */
abstract public int concat(int parentCS, int childCS);

/** Create a new coordsys whose transformation
 * is the inverse / pseudoinverse (i.e. if the
 * original transformation is singular / near-singular,
 * use closest reasonable value) of the 
 * given coordinate system.
 */
abstract public int invert(int coordsys);