XAS-90 Remove duplicate variable

THERE ARE TWO ATTRIBUTES CALLED DATAPORT!!!!!!

A historical problem, so its amazing this has never caused a bug before.
fix bug where the value was being saved incorrectly and so the scannable
would report the wrong position
Added logic to handle PyFloat objects
removed system.out message
Merge branch '8.30' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into 8.30