refactor stencil generation
refactor stencil generation

jriehl/numba,stonebig/numba,gmarkall/numba,seibert/numba,sklam/numba,sklam/numba,seibert/numba,cpcloud/numba,stonebig/numba,numba/numba,jriehl/numba,cpcloud/numba,seibert/numba,stuartarchibald/numba,jriehl/numba,seibert/numba,gmarkall/numba,numba/numba,gmarkall/numba,sklam/numba,stuartarchibald/numba,IntelLabs/numba,stuartarchibald/numba,stonebig/numba,jriehl/numba,numba/numba,cpcloud/numba,sklam/numba,stuartarchibald/numba,stonebig/numba,numba/numba,gmarkall/numba,gmarkall/numba,IntelLabs/numba,jriehl/numba,cpcloud/numba,stonebig/numba,IntelLabs/numba,numba/numba,stuartarchibald/numba,sklam/numba,seibert/numba,IntelLabs/numba,cpcloud/numba,IntelLabs/numba