Added MCNP interface for source sampling.
Changed tag names and mode indexing (MCNP idum numbers are indexed from 1).
Doc strings.
updated serp for v2 for res
updated detectors for serpent 2
Merge pull request #513 from scopatz/s2

Serpent 2 Updates
SG fixes
Made Fortran API non-specific for MCNP.
Starting documentation.
Adding doc file.
fix SG for underscores to close #490

also cleanup trailing whitespace
leading -> trailing underscore
fixes #476
Merge pull request #514 from crbates/sgus

fix SG for underscores to close #490
All code in documentation works.
Final Cleanup.
Merge pull request #515 from crbates/fpyfix

fixes #476
Removing source.F90
Added new source.F90
Merge pull request #512 from elliottbiondo/fortran

Fortran interface to Sampler class