Exotherm - Evaluator tweaks

I recently adjusted Exotherm's position evaluator a little more. To help it avoid losing in preventable ways in the endgame, I made it value check by rook or queen, which tend to lead to explosions. To encourage it to develop more pieces in the opening, I made it slightly value the possibility of targeting more open squares. I also adjusted the pawn balance evaluator to be less likely to needlessly sacrifice a rook for a pawn.

There's still no updates on FICS's provisioning of a computer account for Exotherm.