Update ChessMoves.cpp

Implemented "move" and "from_algebraic" (see ChessPosition.h).

Currently, "from_algebraic" uses especially regular notation:
"pe4" <-- pawns have letter
"Nf3"
etc., even for taking.

Future upgrades:
allow "x"-notation for taking, "="-notation for pawn promotion, and "O"-notation for castling.

Note that the finished game will __not__ have any of these time-dependent rules:
*draw after 50 quiet moves
*draw by repetition
*en passant
*castling allowed only between untouched pieces.

also,
*king may move into check, so
*castling through attacked squares will be OK, and
*checkmate is irrelevant: the goal's to capture the king.