added an onloopsend hook to the end of the dijkstras algoritm loop. now the negitvie weighted will call the dijkstrasalgoritm recursivle if the loop is walked trough

to prevent a stackoverflow pathvertex got an recursive resetstatus function.
fixed a toString bug where te first element was not printed.

added a prepTostring method in the positiveweigted strategy so the negative weigthed strategy could use this in preping the vertexes for the to string method
expended the test to test for negative loop cycle.