Fixed the LRA.py bug, which was 0-based versus 1-based getters.  Switched all the getters and setters for scattering matrix to be (origin,destination) -- making the order consistent and using more meaningful names than (group1,group2).  Added inline function for mapping of scattering matrix.
Moved inline function inside Material class.
Merge branch 'scattering_fixes' into develop
Cleaned up the inline function calls a bit.
Addressed Will's comments on the patch.
Merge pull request #93 from PrezNattyGibbs/develop

LRA Bug Fix, Error Messages, and Scattering