Board::find_pieces returns a BitBoard for all the pieces matching the given Piece.
Board::enemies returns a BitBoard of all the enemy pieces of a given Color.
Board::pawns returns a BitBoard of all the pawns of a given Color.
Let BitBoard::rank and BitBoard::file take a Rank and File directly, instead of a
u8 by reference. And then make the Rank/File::as_index const and return a value
rather than a reference.
All this allows you to convert between Rank, File, and BitBoard at compile tile
(i.e. as a const method) rather than needing to do runtime stuff.
New convention: active_color_ methods operate on the active color of the Board.
Methods without that prefix take a color parameter and operate on that.
Refactor opposing_sight to do this.
Implement a new method on Position that evaluates whether the active color can castle
on a given wing of the board. Then, implement making a castling move in the position.
Make a new Wing enum in the core crate to specify kingside or queenside. Replace the
Castle enum from the board crate with this one. This caused a lot of churn...
Along the way fix a bunch of tests.
Note: there's still no way to actually make a castling move in explorer.
Add two BitBoard attributes to the struct that mark squares that should be marked
or highlighted.
Empty marked squares are shown with an asterisk (*). Marked squares with a piece
don't have any change of appearance. (Something I'm still thinking about.)
Highlighted squares are shown with the ANSI escape sequence for Reverse Video.
Encapsulate castling rights within a small module. Castle provides the API to the
rest of the board package. Rights encodes the castling rights for each player.
Parameters defines castling parameters for each player.
Now that board has a Mailbox, the implementation of this routine can be greatly
simplified. Instead of needing to iterate through all BitBoards to find the
occupied square, just consult the mailbox.
