converted findMaximumMatching to free function
added errors to gitignore
renamed graph to directed graph
added directed weighted graph
changed name of method from nodes to numOfVertices
added numOfVerticesFromFirstSet and numOfVerticesFromSecondSet methods
BipartiteGraphTest addEdge_tooBigIndex
added consts to methods and DirectedGraph member to BipartiteGraph
used directed graph in bipartite graph for edge existance checking
added directed tree
DirectedTreeTest addEdge_neverCreateCycle_alwaysConnected
(DirectedTreeTest, addEdge_disconnectedCheck)
addEdge_incomingToExistingVertex
(DirectedTreeTest, addEdge_loopOnOneVertex)