Removed backup files.
Added possible moves for all the pieces.
Included height to describe the board size.
Added number-of-moves attribute to the piece.
Fixed possible moves to pawn.
Revised print-board to use upper case to black pieces and lower case to white ones.
Created generic functions to get the valid moves over the board by walking into a single direction.
Revised functions to retrieve valid moves for each piece type.
Created function to play a move sequence.
Source code refactored into multiple files.
Added documentation to the functions. Revised the coordinates handling.
Revised functions that handle the board to use the datatypes Square e Piece.