XAS-5 add some space into the 'start queue' button text so that when it
switched to 'pause queue' the buttons are not adjusted too far.

This is a problem with XAS client where extra buttons are added to the
toolbar and they are pushed out of line when the queu is started.
Merge branch '8.26' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into 8.26