Move graph property algorithms to new Algorithm\Property
Add tests with 100% coverage for new GraphProperty algorithm
Move Walk property algorithms to new WalkProperty algorithm
Add WalkProperty::hasLoop() alias (completeness)
Fix WalkProperty::hasCycle() by checking correct array of vertices
Fix accessing invalid graph property due to moving algorithm
Fix testing digons and triangles due to moving algorithm
Fix checking hamiltonian property in cycles
Fix Walk::isCycle() by rejecting walks with no edges
Add tests with 100% coverage for WalkProperty algorithm