QMult:

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   Multiply two quaternions.
   Q2 transforms from A to B and Q1 transforms from B to C
   so Q3 transforms from A to C. If only one argument is input
   it produces the 4x4 matrix equivalent:
   q3 = Q2*q1;

   Since version 1.
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   Form:
   Q3 = QMult( Q2 ,Q1 )	
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   ------
   Inputs
   ------
   Q2              (4,1)  Quaternion from a to b
   Q1              (4,1)  Quaternion from b to c

   -------
   Outputs
   -------
   Q3              (4,1)  Quaternion from a to c or 4x4 version of q

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