#733 Method to specify seed for ran. gen. in OBConformerSearch

[Martin Kamp Jensen]

The OBConformerSearch class uses the current time as the seed for the random generator used to create the initial population and the next generation populations. This means that the results cannot be recreated. It would be nice to have a method that allows one to specify the seed thereby enabling easy recreation of earlier results given the same input. The default seed can (and should probably) still be the current time.