Cubeo variants

[mcdemarco]

I added Cubeo "dice" variants to play up to 8, 10, or 12 dice:

            "#dice": {
                "name": "Default die size (d6)",
                "description": "Each player has six d6, and the merge goal is 7."
            },
            "d8": {
                "name": "d8",
                "description": "Each player has eight 8-sided, yet cubical, dice, and the merge goal is 9."
            },
            "d10": {
                "name": "d10",
                "description": "Each player has ten 10-sided, yet cubical, dice, and the merge goal is 11."
            },
            "d12": {
                "name": "d12",
                "description": "Each player has twelve 12-sided, yet cubical, dice, and the merge goal is 13."
            }

I took out the 7 and 9 variants when adding 10 and 12. The 7/8/9 version was less of a code change and is possibly less buggy than the second commit. (Not that I think there are still bugs, but just in case something comes up.)

[Perlkonig]

Cheers!