Initial commit of 100 um Film coating

Initial commit of 100 um film coating.  I am trying to do a more
accurate model, (using some better paramters) and intend to inlcude the
effects of the gap, temperature, etc.
Running reference fuel pin

Completed running reference fuel pin. The keffective is 1.33, which is a
little bit lower than the MCNPX values but is at least believable.
Added git ignore
Added the reference fuel pin

Added a reference fuel pin.  Now investigating what happens if we put
muliple zones / intervals (like where the cladding would go)
Added in 10 um and 100 um simulations

Added in 100 um and 10 um thin layers on the cladding simulations.  I
think that there must be an error as the k-effective changes (but is
stable for both of the materials).
Added various thickness of water

Divided the moderator into two layers, playing with spacing.  When there
are more regions it gives a differnet k, prehaps I haven't counted my
regions properly?
Removed activity calculations

Removed the activity calcuations.
Added fixed meshing

Added the fixed meshing into the calculation which pulls my k-effecitive
down.
Fixed moderator coating thickness

Fixed the moderator coating thickness.  I had incorrectly had 100
microns when it was 10 um.
Increased the mesh size

Increased the mesh size for both cases. There is still some disagrement
between the two cases, but I think it is pretty good.
Added user meshing to the ref (no coating)

Added the user meshing to the ref fuel pin (without any coating) and
observed that it agreed with the other user meshes, but was still a
little bit higher than the XSDRN defaults.