More flexible contribution scheduling options

This suggestion combines a few existing requests with some new ones of my own...

Essentially I'd like to see many more options to schedule contributions than just once per month. There should be two selections as follows:

* First, select a frequency:
-- Once per week
-- Once every two weeks
-- Twice a month
-- Once a month
-- Once every two months
-- Once every three months
-- Once every six months
-- Once a year
-- Manually

* Second, select a starting date

Then, schedule the first contribution on the starting date and the remaining contributions following the selected frequency. Manual contributions would allow for ad-hoc savings without forcing transactions at any particular time.

Thanks!
Alan