prevent NPE
make code clearer to read
More work on line plotter.
Merge branch 'gda-8.40' of ssh://dascgitolite@dasc-git.diamond.ac.uk/gda/gda-core.git into gda-8.40
GDA-6007 Allow JLine to be used for telnet & SSH connections to Jython server
MXGDA-1147 offer staff visits prefixed with nr in addition to cm
DASCTEST-258 restore javax.xml to tp/
Remove all the Jetty & Spring HTTP classes

These were all superseded by the RMI classes, which are actually in use.

Additionally some of the HTTP stuff seems to not be compatible with Spring 4.
Merge remote branch 'origin/gda-8.40'