remove bogus comment
save one check by using sentinel Double.MAX_VALUE for costs
remove() and remove(E) use common helper siftDownUp(index)
use copyData instead of moveData for removeSiftDown
early abort as leftChildIndex < rightChildIndex
remove tail recursion in removeSiftDown()
new trivial test
new performance test, output time for each step
assertEqualsHE()
split BinaryMinHeapTest