Support algebraic notation.

[smenjas]

See: Wikipedia: Algebraic notation (chess)

There are different kinds of notation:

• FIDE
• Portable Game Notation (PGN)
• Abbreviated/minimal algebraic notation
• Descriptive notation
• ICCF numeric notation
• Universal Chess Interface (UCI)

I'd like to:

• define a standard for plain English commentary
• choose a default algebraic notation (based on FIDE, PGN, and/or UCI)
• allow translation between different formats
• be able to import games in any standard notation
• allow the player to choose their preferred commentary format

For clarity, readability, and data redundancy, consider a custom intermediate notation:

• prefix piece color with B or W
• indicate pawns with P
• note origin squares for each move (equivalent to disambiguated and long algebraic notation)

This is clearer for amateurs, and protects against transmission losses.

I'd like to provide plain English commentary. However, advanced players may prefer algebraic notation. We may want to allow them to choose their preferred format.

Examples:

• Be5: Bishop to e5
• Nf3: Knight to f3
• c5: Pawn to c5
• Bxe5: Bishop captures the piece on e5
• B:e5: Bishop captures the piece on e5
• Be5:: Bishop captures the piece on e5 (note trailing colon)
• exd5: Pawn on the e-file captures the piece on d5
• exd of ed: Pawn on the e-file captures the piece on the d-file (minimal)
• exd6 e.p.: Pawn on the e-file captures the piece on d6 en passant
• Rdf8: Rook from d8 to f8 (disambiguated)
• R1a3: Rook from a1 to a3 (disambiguated)
• Qh4e1: Queen (disambiguated)
• *e2e4: Pawn moves from e2 to e4 (long algebraic notation)
• Nb1-c3: Knight moves from b1 to c3 (long algebraic notation)
• Rd3xd7: Rook moves from d3 to capture the piece on d7 (long)
• e8Q, e8=Q, e8/Q, or e8(Q): Pawn promoted to queen
• 0-0 or O-O: Kingside castling
• 0-0-0 or O-O-O: Queenside castling
• +, †, or ch: Appended to a move placing king in check
• dis ch: Appended to a move placing king in discovered check
• dbl ch or ++: Appended to a move placing king in double check
• #, mate, ‡, ++, ≠, X, or x: Appended to a move placing king in checkmate
• X, or x: Checkmate, when captures are denoted by :
• 1-0: White won
• 0-1: Black won
• (=) or ½–½: Game ended in a draw
• 0–0, ½–0, 0–½: Forfeit
• +/−, −/+, or −/−: Win by default