SBML import ignores `useValuesFromTriggerTime` attribute on events

[dweindl]

Copied from the libsbml documentation:

The optional Delay on Event and the fact that multiple events may be simultaneously executed means there are two times to consider when computing the results of an event: the time at which the event is triggered, and the time at which assignments are executed. It is also possible to distinguish between the time at which the EventAssignment's expression is calculated, and the time at which the assignment is made: the expression could be evaluated at the same time the assignments are performed, i.e., when the event is executed, but it could also be defined to be evaluated at the time the event is triggered.

This attribute is currently ignored by AMICI.

The attribute should be checked, and an exception should be raised if the selection is not supported.

It seems like the SBML test suite doesn't have a non-delay test case with useValuesFromTriggerTime=True and where that makes a difference.