core: switch to generalized NewBoard with seed arg
engines: switch to new NewBoard call
core: split Size into Rows and Cols
engines: remove a Board.Size() reference from dispatch.go
core: fix a row/col mixup
engines: extend boardsize GTP command in dispatch.go
core: a go fmt fix in board.go
core: refactored star-point marking supporting nonsquare boards
core: better unit test coverage of nonsquare boards