add compatibility for float and integer (refs #3825, refs #3811)
add reference date for timer (refs #3829)
reset dynamic timer only if reference date has changed (refs #3829)
update dynamic timer documentation (refs #3829)
Merge pull request #764 from Eric-Brison/3.2-I3829

Dynamic Timers (closes #3829, closes #3825, closes #3811)