validate vertex ids implemented and tested
integrated inline suggestions
Merge pull request #36 from andralungu/graph-validation

validate vertex ids implemented and tested
Added PageRank example
Added PageRank as a library method and example
PageRank example implementing GraphAlgorithm
Merge pull request #30 from ktzoumas/pagerank_method

GraphAlgorithm interface and Pagerank example
first take on neighborhood methods: OutEdges
fixed type info for the outEdgesFunction
use vertex/edge instead of tuples in the test
fixed a few warnings in pagerank example
some refactoring and cleanup
reduceOnEdges method for in-/out- and all edges