updates basic data structures

- updates methods for abstract Node and Graph classes
- adds interfaces for weighted nodes / edges
adds guava library

http://code.google.com/p/guava-libraries/
removes preliminary weights

removes the classes for representing weights
now, weights are stored directly in the node / edge
adds edges / nodes containers

adds containers that hold the set of edges / nodes
implement the basic operations required by a graph
adds update types and batch container

adds all six update types
- node / edge addition
- node / edge  removal
- node / edge weight update
adds batch as container for a set of updates
adds BatchGenerator

basic class
extension for directed graphs
basic implementations for directed graphs
adds GraphImpl

abstract class that iplements the Graph interface using the methods
provided by the Edges and Nodes containers
updates / adds GraphDataStructures
updates GraphGenerators
updates basic datastructures for directed graphs
updates basic datastructures for undirected graphs
adds keywords

adds delimiters for updates
update undirected random graph generator
adapts graph structures to GraphImpl

now all existing graph structures use the container method offered by
GraphImpl
adds weighted directed nodes / edges
adds new directed graph structures
adds undirected weighted edge
adds clique and ring directed graph generators