Merge remote-tracking branch 'origin/master' into add-vertices-class

Conflicts:
	lib/Fhaculty/Graph/Algorithm/Degree.php
	lib/Fhaculty/Graph/Edge/Base.php
	lib/Fhaculty/Graph/Edge/Directed.php
	lib/Fhaculty/Graph/Edge/UndirectedId.php
	lib/Fhaculty/Graph/Graph.php
	lib/Fhaculty/Graph/Vertex.php
	lib/Fhaculty/Graph/Walk.php
	tests/bootstrap.php
Add type hints for autocompletion
Fix ordering by degree (Algorithm\Degree)
Add Set\Edges::getEdgesIntersection()
Return set of Vertices in Edge::getVerticesStart() and *Target()
Fix getting parallel undirected edges
Fix accessing Sets of Vertices and Edges
Fix assertions on Sets
Always use Set\Vertices and Set\Edges instead of working with arrays
Fix checking Edges in Walk::isValid()