TEMPORARY: always draw the pdep networks.

This is presumably a runtime penalty, or at least a hard disk space penalty,
and probably shouldn't be a default. I guess we could make it optional.
Or else drop this commit. 

But it's nice for debugging.

Author: rwest

rmgpy/rmg/pdep.py

@@ -868,6 +868,7 @@ def update(self, reaction_model, pdep_settings, requires_rms=False):
         if output_directory:
             job.save_input_file(
                 os.path.join(output_directory, 'pdep', 'network{0:d}_{1:d}.py'.format(self.index, len(self.isomers))))
+            job.draw(os.path.join(output_directory, 'pdep'), filename_stem=f'network{self.index:d}_{len(self.isomers):d}', file_format='pdf')
 
         # Calculate the rate coefficients
         self.initialize(Tmin, Tmax, Pmin, Pmax, maximum_grain_size, minimum_grain_count, active_j_rotor, active_k_rotor,