added decrement operator
minor changes - different names of functions
added eachNode() and eachEdge()
added eachNode() and eachEdge()
added graph.eachNode() and graph.eachEdge()
added graph.eachNode() and graph.eachEdge()
added graph.eachNode() and graph.eachEdge()
Merge pull request #49 from mkarlovc/master

eachNode() and eachEdge() added