Make more modules available for library use?

[liamoc]

Hi, I'm making a Chess GUI in Rust and I just want to link directly to littlewing rather than run it as a separate process.

But many modules are not public which makes it quite difficult. In particular, determining if a player is in check (the attack module), or access to the PieceMove type would be super helpful!

[vinc]

Hi @liamoc, thanks for opening this issue, I could indeed make more modules public, I'll look into it!

[liamoc]

Great, thanks!

For this chess GUI I just had to make the attack and piece_move modules public. I can submit a PR but it's a very minor change.