Clarified the looping logic of GEBrain.searchAllyVisibleSquares, and instead incorrectly of passing a very large number (901) as currentDepth, as a remnant from when it was maxDepth that was passed, m_vision is used directly.

Improved the isSurvivable-* methods of GEUtil, so that they will return true (survivable) for a snake tail position every round after the next growth, rather than only on growth rounds.

Also added a few assertions to ScoringPair.getScore(), to make sure the is allways a valid double value.