Factored out grid from goban + bicolor only
Use of Grid and new XY_DIAGONAL

No more "mark a spot"
Better potential territory using grids
Use of Grid
Bicolor + use of Grid
Bicolor
Added missing tests
Bicolor
Use of Grid and bicolor
Include goban instead of stone
Use Grid
Updated tests for bicolor and Grid changes etc.
Updated tests for bicolor and Grid
Use of Grid, new method count_as_dead
Bicolor, use of Grid
Use of Grid, bocolor, better score counting
Use of Grid
Use of Grid, bicolor
Use of Grid, no more end_scoring
Use of Grid instead of goban