"Time" extreme value postprocessor

[permcody]

Description of the enhancement or error report

I need the ability to record a max/min value of an arbitrary postprocessor. This isn't possible despite all of our parsed function capability.

Rationale for the enhancement or information for reproducing the error

This will be useful in normalizing timing studies that have variation in something like DOFs that vary due to adaptivity.

Identified impact

(i.e. Internal object changes, limited interface changes, public API change, or a list of specific applications impacted)

New capability (no impact)