added optional parameter of graph to getSymbolikPaths

This fixes an issue where when a user specifies list of paths to getSymbolikPaths, the function creates a new symbolik graph. The new graph wont have edge id's that line up with the supplied paths and therefore will exception on line 583. 

The fix requires when specifying paths to also specify a graph otherwise an exception is thrown.
is this still an issue with the merger of the atlas delta that added a graph param? maybe just so port over the extra check? ( his pull had a bunch of other stuff in it as well )