Fix Issues #2036 and #1973: Changed currentDate comparisons to minDate and maxDate to be inclusive

[gobrien37]

Issues #2036 and #1973 refer to crashes when minDate or maxDate are equal to currentDate in the datetime module datePicker. This request changes the checks for minDate and maxDate validity to allow for these dates to also be the currentDate.

[eygraber]

Any idea when this will get merged? It's pretty bad behavior.