First pass at gpu-ification.

Added build infrastructure to link to the cuda runtime and
magma.  Just set IFCUDA=true in makenek

Ported local_grad3 in the simplest possible way using magmablas.

Changed the test size to be of higher spectral order and fewer elements
for rapid prototyping.  On my system, GPU outperforms CPU by ~30%
(single GPU, single core: not fair at all).