Add comments on round_to algorithm source and delete commented code
Add comments on round_to algorithm source and delete commented code

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