Compositon in wt fraction

Added the composition to be a weight fraction.
NITWAL block completed

The NITWAL block is completed, but it is not checked.
XSDRN Data Block 1 Complete

Completed the first data block of XSDRN (expect for the MS) card, which
I don't know what it does.  I am currently not using flux collaposing.
XSDRN Data block 2 completed

Completed writing the second data block for the XSDRN input deck.  The
material composition is a bit fuzy, but I think I worked it out.