refs #9569. Expose CatalogManager.

Add python tests for new behaviour
refs #9569. Expose CatalogSessions and test.
Merge remote-tracking branch 'origin/feature/9587_alg_documentation'
Merge remote-tracking branch 'origin/feature/9800_sphinx_warnings'

Re #9800.

Conflicts:
	Code/Mantid/docs/source/algorithms/LoadDetectorInfo-v1.rst
	Code/Mantid/docs/source/algorithms/OneStepMDEW-v1.rst
	Code/Mantid/docs/source/algorithms/SANSWideAngleCorrection-v1.rst
refs #9569. Use ICAT in ReflGUI.

Have added extra options on the options dialog to enable/disable this, but have not wired everythin in yet. Will also need to uncomment and test that the old code still works.
refs #9569. Allow switchable behaviour.

Warn if ICAT search without ICAT download.

Enable the Journal searching as the default.
refs #9569. Fix merge conflict and other errors.

Merge branch 'master' into feature/9569_icat_for_refl

Conflicts:
	Code/Mantid/scripts/Interface/ui/reflectometer/refl_gui.py
Merge branch 'feature/9569_icat_for_refl' into develop

Conflicts:
	Code/Mantid/docs/source/algorithms/LoadDetectorInfo-v1.rst
	Code/Mantid/docs/source/algorithms/SANSWideAngleCorrection-v1.rst