Some cleanup, statically link OpenSSL

I've tried to clean up the code base a bit and extracted the function prototypes and `#define` pragmas into a `sslscan.h` header.

I also enabled a one-shot local compilation and statically linking of OpenSSL via the `static` make target.

As a bonus, I retagged the commits so that the build process can facilitate `git tags` to get version information.