Working Code. Huge Fix of Errors.

Now the code is working, left to implement is text output interface.

Changelog:
Digrafo - contains like methods and iterators
Grafo - boolean fix
GrafoPonderado - boolaen fix
Nodo - Serializable
IOGrafo - yet to text text interface and extension fix
JAristaDialog - Panels added and working Modality
JCreator - Added createComboBox
JVentana - Huge fix and improvements