Trivial changes to .gitignore.
Cleaned Heuristic.
Instead of getHeuristics() returning an array, HeuristicList now has get() returning one Heuristic.
Zero-weight heuristics are now allowed. (There's probably no reason to create such a thing, but also no reason to forbid it.)
Finished cleaning HeuristicList.
Removed unneeded features from SpecificPointHeuristic. Also made clone() methods in some classes in orego.heuristic safer (in case subclasses fail to implement Cloneable).
Merge branch 'master' into clean