[Druid::Game] made make-move return the move on success
[Druid::Game] made make-move return the move on success

So, it turns out that Nil ~~ Failure. Who would have thought? Made the method
return the move just made. This seems as useful a defined value as any.

Also renamed some variables s/last/latest/.

zoffixznet/druid,zoffixznet/druid,masak/druid