fixing bugs with parameterization.
Fixing bugs with parameterization.
Set things up for implementing parametrized short answer problems.
added in a set of possible short answers for parameterized short answer problems.   This includes saving a list of short answer possibilities in the student state when the binding is done so that grading student inputs checks against values appropriate to the bindings being used.
ADded in the $Best_Answer to the variable bindings sent to the client.   This meant cloning the Binding maps so adding in this value didn't add it permanently into the objects that live in the Problem objects in cache.
Some changes to parameterized problems.
Committing to merge.
Fixed parametrization with quickAuth problems.
Fixed a bug where parametrized problems get bound more than once.
Merge branch 'master' of https://github.com/marshall62/mathspring