Groveller feature proposal: include-local

Aim: Add include-local to the groveller. Behaviour: - uses #include "name.h" rather than #include <name.h> - expects the header file to be local to the wrapper/groveler specification file. This file is copied to the cache dir (with the generated c file) so it can be used in the build. Reason: This allows us to wrap single header libraries simply by making a wrapper spec containing

(include-local "some_header_lib.h")

I'd love to hear some thoughts on this. I'm happy to get this done if it's approved. Regards Chris