Added Infomap community detection algorithm

The algorithm performs double faster than previously implemented (slow) Girvan-Newman algorithm. According to the references (Rosvall M., Bergstrom C. T., Maps of random walks on complex networks reveal community structure, Proc. Natl. Acad. Sci. USA 105, 1118-1123, 2008), the algorithm could perform much faster, so the implementation can be improved. Comparative analysis of most used community detection algorithms (S. Fortunato and A. Lancichinetti. 2009. Community detection algorithms: a comparative analysis: invited presentation, extended abstract) showed good quality of detected communities.