DCDM RDT Clips XYZ values incorrectly

[aforsythe]

rdt_dcdm.ctl currently clips XYZ values to 0-1 range.

// Clip  data to range zero to one
XYZ[0] = clip_0_to_1( XYZ[0] );     
XYZ[1] = clip_0_to_1( XYZ[1] );     
XYZ[2] = clip_0_to_1( XYZ[2] );

This is incorrect as XYZ values should be allowed to range over 1.0.
The XYZ values less than 0 should be clipped to 0.