Re #6096. Remove unused and incorrect method.

It didn't account for parameterized instruments and was only
being used in a single test. Instead, getMonitors() followed by
getDetector() can be used.
Re #6369. Only emit the filesFound signal if something's been found.
Re #6096. Add const qualifier to a method that deserves it.
Re #6096. Log removal error at a lower level for hidden workspaces.
Re #6371. First parts of GUI for dealing with rocking curves.