Issue #1396536, Repeating fields weren't getting created with Devel Generate because of the change in widgets. Add new hooks so Date Repeat Field can add the repeats.

Issue #1236216, Start the process of moving the repeating date integration out of the Date module and into a separate, Date Repeat Field module.

Issue #1234140 by arlinsundbulte, Change terminology in user-facing text from 'From/To Date' to 'Start/End Date'.