New feature: Automatic smoothing + Bug fixes

Created by: AlecThomson

Adds the ability to automatically determine after imaging. This uses radio_beam to find the smallest common beam. To accomplish this, I've moved smoothing to the build_cube stage. This has the disadvantage of running in serial. We could perhaps spin this out into its own script to allow it to run using a job array for each channel.

I've also included a couple of bug-fixes - this mostly affects the report script. It now uses casatasks to sniff the MS, and fixes some pandoc commands.