add sequence generation

[tjayrush]

Feature Request

Is your feature request related to a problem? Please describe:

Describe the feature you'd like:

It would be nice if I could write something like carbon.Sequence("sunday", "2:00pm", 12) to produce twenty repetitions of Sunday at 2:00pm (or similar, of course).

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

I would use this to generate dates for some blockchain related software I'm working on that would then query for the block numbers at the given dates. In this way, i could generate account balances and do something akin to weekly profit and loss statements on my accounts.

[gouguoyin]

Please give an example of what is the return result of carbon.Sequence ("Sunday", "2:00pm", 12)