Fixed runtime resource resolution during rendering

I've updated XsltStylesheetManager to include methods and arguments
for specifying the 'runtime' ResourceLocator to use. This has been
integrated into AssessmentRenderer so that the XSLT can load
resources relative to the assessment XML using the ResourceLocator
provided by the caller.
Fixed missing item title in test-item.xsl
Updated sample test delivery settings slightly
Minor tweak to default test del settings
Fixed regression in item XSLT (uncommitted resps)

The XSLT didn't know about the new uncommitted vs. committed
response variables. It how handles both, though doesn't care
about the difference.
Improved template generating session control opts
Minor documentation fix
Added 'return null' after logAndForbid() calls

This is for clarity and consistency only - logAndForbid() will actually
call an unchecked exception so processing won't continue anyway.
XSLT: Item status now handled uncomm'td responses
Minor tweaks to buttons in test LINEAR mode:

1. Finish Question -> Next Question
2. Added 'End Test(Part)' button

NB: 2 has revealed a bug in L/S mode. Will fix and commit
shortly.
Fixed missing check in RunAssertions
Fixed TSController: advancing items in L/S mode

This was previously ending the item session, which was the
wrong behaviour in S mode. The logic now behaves better
(suspending the session instead of ending it).

NB: I changed the name of this method to advanceItemLinear()
as endItemLinear() is no longer accurate. The corresponding
mayEndItemLinear() has been renamed as mayAdvanceItemLinear()

I have added a unit test for this.
Improvement to "Review" button + action names:

* Tidied up action names to reflect changes to 'advance item' in linear
mode.
* Improved the rendering of the "Review" buttons to clarify when it's
worth clicking on the button, as well as showing further info about what
the client had done with that item.
Finally added C->PMathML to rendering pipeline...
Fixed some uses of Content MathML in UPMC examples
Marked some UPMC samples as being templated
test XSL: "View item source" -> "View test source"
Minor tweak to anonymous upload/run

I've clarified that we only let the user choose delivery
settings when uploading an item. For tests, some defaults
will be used.