IConv:

--------------------------------------------------------------------------
   Transform a 6x1 compact inertia vector into a 3x3 inertia matrix.

   Vector form:   [Ixx; Iyy; Izz; Ixy; Ixz; Iyz]

--------------------------------------------------------------------------
   Form:
   IMat = IConv( IVec );
--------------------------------------------------------------------------

   ------
   Inputs
   ------
   IVec          (6,1)    Compact inertia vector

   -------
   Outputs
   -------
   IMat          (3,3)    Full inertia matrix

--------------------------------------------------------------------------