Allow C++ compilers to include the badge headers.

[osresearch]

Wraps all of the headers with __BEGIN_DECLS and __END_DECLS so that C++ compilers like the Arduino framework can include the badge component headers.

[osresearch]

Thanks for the merge! __BEGIN_DECLS / __END_DECLS tells the C++ compiler that the functions in that block are C functions and should not undergo name mangling. On C they are NOPs. They expand to:

#ifdef __cplusplus
extern "C" {
#endif

// externs go here

#ifdef __cplusplus
};
#endif