Converts 'capsicum.h' to C code

This pull request updates the included 'capsicum.h' file to be C code, rather than C++ code. The tests still compile and pass. Additionally, users may now include this header in their other C (or C++) projects to provide access to capsicum features. The capsicum-linux project doesn't create this header file anyplace on the system, so the version included in this project is the best place for Linux users to grab it.

The conversion was trivial and consisted of replacing the bool type and it's values with the corresponding int representations.