Added makefile for shamrock.  Also added gitignore to src/ to prevent object files from being committed.
Added makefile for shamrock.  Also added gitignore to src/ to prevent object files from being committed.

cholla-hydro/cholla,cholla-hydro/cholla,evaneschneider/cholla,cholla-hydro/cholla,cholla-hydro/cholla,evaneschneider/cholla,evaneschneider/cholla,evaneschneider/cholla