Issue when using savu_mpijob_local.sh 

savu_mpijob_local.sh only seems to run when `from . import pre_run as pr` is changed to `import pre_run as pr` in tomo_recon.py.

Otherwise:
`ImportError: cannot import name 'pre_run' from '__main__' (/home/.../anaconda3/envs/savu/lib/python3.7/site-packages/savu-4.2-py3.7.egg/savu/tomo_recon.py)`