Add formatDate/Time methods
Add formatDate/Time methods

Add formatDate, formatTime and formatDateTime functions.
Improvements versus DateHelper->date:
- they accept almost any date/time representation
- they respect the user/app timezone
- no dependency on defines

avdevs/concrete5,TimDix/concrete5,TimDix/concrete5,avdevs/concrete5,matt9mg/concrete5,TimDix/concrete5,MichaelMaar/concrete5,MichaelMaar/concrete5,matt9mg/concrete5,matt9mg/concrete5,MichaelMaar/concrete5,avdevs/concrete5