0.7.0 :
* Add option "path" to output

0.6.0 :
* Add undirected graph support

0.5.0 :
* Preserve the original order of creation of nodes and edges

0.4.0 :
* Add HTML-Labels

0.3.0 :
* Bugs corrections

0.2.0 :
* Pure ruby

0.1.0 :
* Initial version