Redid the materials

I redid the materials so I could understand them
Added the nitwal block

Added the nitwal block to the simulation
Corrected XSDRN Block one

Corrected the first XDRN Block
Fixed 40091 to 4091 isotope
NTIWAL block executes
Working run!

Working run.  The larger error was in that I didn't end the last block
propertly.
Added the compositions