GO graph, cluster/tsgraph

- [*] remove the generic type T and define NodeSet/EdgeSet instead
- [-] remove the no-longer-required  type Node &type Edge
- [+] define nodeSet & edgeSet, ie. set of pointers to nodes & edges directly
      within the graph. Thus fixed the endless loop (because of newly created
      pointers) problem
- [*] replace nodeCollection with nodeSet

GO graph, cluster/cluster

- [*] use nodeSet & edgeSet instead of generic set
- [*] use gographviz.Node & gographviz.Edge instead of previous
      cluster.Node & cluster.Edge
- [!] deleted visited Node/Edge right away before testing hasVisited
	to fix the previous endless loop problem
- [-] disable all debug output
- [!] fix the bug that already-visited hub nodes not being
	added to the following sub-graphs

GO graph, gtest

- [*] now is a fully functioning program:

  go run gtest.go gtest.fin 23 > gtest.fout