Added some docstrings.  Modified where and how DUFuncKernel subclasses are built to improve readability.
Added some docstrings.  Modified where and how DUFuncKernel subclasses are built to improve readability.

gdementen/numba,seibert/numba,jriehl/numba,stuartarchibald/numba,pombredanne/numba,cpcloud/numba,GaZ3ll3/numba,pitrou/numba,sklam/numba,GaZ3ll3/numba,sklam/numba,IntelLabs/numba,jriehl/numba,numba/numba,jriehl/numba,stonebig/numba,stuartarchibald/numba,cpcloud/numba,gmarkall/numba,sklam/numba,stonebig/numba,seibert/numba,cpcloud/numba,pitrou/numba,numba/numba,numba/numba,pitrou/numba,IntelLabs/numba,ssarangi/numba,stefanseefeld/numba,cpcloud/numba,gmarkall/numba,GaZ3ll3/numba,stonebig/numba,gmarkall/numba,pombredanne/numba,stefanseefeld/numba,pitrou/numba,gmarkall/numba,pitrou/numba,numba/numba,seibert/numba,pombredanne/numba,gdementen/numba,jriehl/numba,jriehl/numba,stuartarchibald/numba,gdementen/numba,stefanseefeld/numba,sklam/numba,stuartarchibald/numba,IntelLabs/numba,pombredanne/numba,stonebig/numba,seibert/numba,GaZ3ll3/numba,gdementen/numba,sklam/numba,cpcloud/numba,ssarangi/numba,gmarkall/numba,stefanseefeld/numba,pombredanne/numba,numba/numba,stefanseefeld/numba,gdementen/numba,IntelLabs/numba,stonebig/numba,ssarangi/numba,IntelLabs/numba,stuartarchibald/numba,seibert/numba,ssarangi/numba,GaZ3ll3/numba,ssarangi/numba