Support Go variants

Eventually, we should support and consider a wide array of rule sets. Suggested variants include:

* Capture Go
* Territory Go
* Tsumego Time Trials 
* Friend's List
* Blind Go 
* One Color Go 
* Bomb Go
* Hidden Move Go
* Rengo
* 3v3 & 4v4
* Flower Go (3 way or 4 way Go)
* Batoo (look it up)
* Custom Go (Make your own rules)
* Tsumego Maker