Present API for pufferfish

[merkys]

TwoPaCo is used by Pufferfish which currently embeds a patched code copy of TwoPaCo. Patches seem to transform main() function to make it callable in C/C++ code circumventing the command line interface. Would it be possible to merge Pufferfish's patches to TwoPaCo? This way Pufferfish could be linked against static/shared library of TwoPaCo. In addition, I believe such command line-circumventing API could be useful for other users of TwoPaCo preferring static type checking, for example.