-------------------------------------------------------------------------------
   Draw a thermal diagram.
   Shows each node and a line where there is conductivity or
   radiative heat transfer between nodes. 
   First you initialize the routine

   tag = DrawThermalPlugIn( 'initialize',g, hFig, position )

   where g is a CAD model with the added field 
   thermalNet which is struct with fields, b, the input matrix,
   k, the thermal conductivity matrix, and l, the radiative coupling
   matrix. Each matrix is n-by-n where n is the number of components.

   To update write

   DrawThermalPlugIn( 'update', tag, t )

   where t(k) is the temperature of component k.

   Each node is colored based on the temperature. You an set the maximum
   temperature by writing

   DrawThermalPlugIn( 'set max temp', tag, tMax )

   Has a built-in demo using ThermalCube.

-------------------------------------------------------------------------------
   Form:
   DrawThermalPlugIn( action, modifier, hFig, position )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   action      (1,:)  Action
   modifier    (1,:)  Modifier to the action
   hFig        (1,1)  Handle to the figure or if 'update' is jD
   position    (1,4)  [left bottom width height]

   -------
   Outputs
   -------
   tag         (1,:)  The tag that identifies the display   

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