Add SymmetrySearch object
Add SymmetrySearch.KindCounts type
Add SymmetrySearch.symmetryGroup
Add SymmetrySearch with external API spec
Add SymmetrySearch.{BoardClass, Guess}
Add naive SymmetrySearch implementation
Replace underlying implementation for Board.findSafePlacement
Pass spec for SymmetrySearch finding a single board when given no pieces
Eliminate duplicates by implementing hashCode on Board
Drop lazy qualifier from Board.safeSpace
Ensure transforming a Board through a Symmetry does not recalculate it's safeSpace from scratch
Add failing test case for number of pieces in result boards