Modify makefile to allow 'compiler=<path>' command line argument
Make small modifications to sweeperUtils

Added nmesh to ModMeshType.

Also removed expoa and expob and replaced them with ExpTableDatType
Make two small changes to sweeper

1. Add ALLOCATABLE attribute to XSMesh(:)
2. Add expTableDat member
Added populateData() routine to IO
Added call to populateData() in main program
Added MPACT dump file for 1-group pin cell