Fixed NPE in renderItemEventWhenClosed()

This was due to the itemEventType possibly being null. The new
logic simplifies things, but will need changed when we support
solutions.
Updated to use more recent examples
Test item rendering now shows sections & rubrics

I have put the post-selection/ordering testPart structure
and rubrics into the rendering for each item, to see how this
looks.

Tidied up the navigation & feedback XSLT and CSS a bit to make
things a bit more uniform.
Added simple-nonlinear-individual.xml test + items
Further improvements to N/I testPart rendering

* Now does testPart feedback
* XSLT tidied up a bit more
* Renamed XSLT for testPart feedback
* Updated Simple NI example a bit more
Rationalised test-related XSLT & render requests
Changed colour for 'review' state to pink(!)
Created simple N/S sample from N/I.
Further work on test rendering, adding "show soln"
Renamed SUBMIT -> SAVE when in simultaneous mode
Updated status of test implementation
2 samples updated to use showSolution=true
Fix earlier SUBMIT -> SAVE (doh!) + authorMode
Minor tidy to CTestDeliverySvc
Added note to say these examples were a bit poor!
Added simple linear navigation test samples
Moved currentl-unused "George" tests for pillaging
Fixed logic bug in TestSessionController

(I was closing the item session when advancing to the next
item in linear mode, which was the wrong thing to do.)
Ready for 1.0-DEV22