Makefile add and gridding code fixes

Makefile expects Halide next to root of RC git repository. If RC is in /home/user/work/RC, then put Halide to directory /home/user/halide

Make builds gridding executable which, when run, should produce C++ code.

Right now Halide complains about non-pure definition of G. I am on the search for problematic part of code.
Fix in G code.

Working on gridding, now its turn to have impure definition.
Halide gridding expression progress.

Halide errs on the current definition of gridding as having multiple reduction domains.

I thought it is possible to express reduction like that, I was wrong.