fix: `ChessBegin`

[dadavidtseng]

[remote] ChessBegin [firstPlayer=]: Start a new match with the named player as the starting player (playing the traditional “white” position), defaults to you if unspecified.
a. Example: “ChessBegin” // start new game with me as first player (adds firstPlayer= to remote command before sending)
b. Example: “ChessBegin firstPlayer=Matt” // I’m starting a new game; Matt goes first
c. Example: “ChessBegin firstPlayer=Matt remote=true” // Matt started a new game, and wants himself to go first