New manager action for M4->M5 migration

Some existing service functionality has moved around to
accommodate this.
Removed 'not null' from ap->aid for deferred set

(I forgot that I'd need this when changing this
to a bi-directional relationship. Logic for setting these up
has been changed appropriately.)
Updated schema migration script for DEV28->DEV29
Fixed regression in Assessment deletion

This broke because of the change in the A<->AP
relationships. Now does things in the correct order
to ensure that FK constraints don't break.
Addd missing images to SToMP samples
Minor tidy to rendering CSS
Removed some left-over author messages in test XSL
Samples list now returns to same group after exit

This makes it a bit easier to browse through the stuff here