Refs #9699

We no longer pass flags separately. By passing them one at a time
directly with notify we bypass a potential race condition and vastly
simplify unit testing logic.

* Run algorithms as children and only put workspaces in ADS at
  the last possible moment

* Cache transmission workspaces more effectively

* Expose TOF and transmission workspaces to the user at the end of
  processing.

Input transmission workspaces were incorrectly failing validation when
loaded with a child algorithm. This was because they were never entered
into the ADS, so they were being wrongly seen as default input values.

I forgot to update the tests after changing the type signature of
askUserString.

Refs #9371.

Conflicts:
	Code/Mantid/MantidQt/CustomInterfaces/CMakeLists.txt

Before, each flag had its own boolean, and its own method to fetch that
boolean. This was all very well, but then to add a new flag you'd have
to add a new method in every child view, and then handle that method in
every presenter that used the view. You'd also then have to fix every
single unit test for the presenters. It was a bit brittle.

This commit replaces that with a single method `getFlag` which pops the
first flag from an internal queue, a flag now being an enum. The
presenter can check if there are any flags waiting to be processed by
calling `flagSet`.

Presenters just fetch the flags until there are no more, and handle them
as appropriate. Views just add the right flag to their internal queue
when they like.

This actually only really needs to be done for the first test case. I've also cleaned up some of the output messages to make them
more accurate and easier to read from the test outputs.