refs #8733. Intermediate changes made. Quick working.

Working well in Quick, but not via the GUI. This is because the GUI uses hard-coded names which make life really really hard! So i'm trying to work around this for now. Not complete yet.

The Parameter file does not get picked up for the newer POLREF IDF, so I am having to add a new one that will be picked up. I have a ticket open where we will completely replace the IDFs, at that point, I can delete this parameter file.
refs #8733. Polarisation corrections hooked in.

This still isn't up to the standard that I would like, but given time constraints, I'm only going to be able to do a little refactoring around these changes.
refs #8733. Extract to methods.

I have very limited time for refactoring this, and we are going to kill this gui completely anyway in the next release.
refs #8733. Merge master in and fix conflicts on branch.

Merge branch 'master' into feature/8733_polarisation_correction_gui

Conflicts:
	Code/Mantid/scripts/Interface/ui/reflectometer/refl_gui.py
	Code/Mantid/scripts/Reflectometry/isis_reflectometry/quick.py
refs #8733. fix naming error.
refs #8733. Check existance before deletion.

When we have group workspaces, if the parent group workspace is deleted first, then it will also remove the children. If that happens, the names previously fetched (which also include the childeren) may be invalid. Checking each workspace before deletion will avoid the invalid delete.
Merge remote-tracking branch 'origin/feature/8733_polarisation_correction_gui'