[TW-1623] Change interpretation of 1 month duration to every xth day of the month

_Andrea Rizzi on 2015-06-14T16:18:35Z says:_

I search for this exact request but I couldn't find it. Sorry if this is a duplicate.

I understand that the concept of monthly duration is intrinsically vague, but with the current interpretation of 1month = 30days taskwarrior is effectively a little less flexible.

I have several tasks that are due the first of the month, and some that are due the first day of the third or sixth month. The user that actually need the task every 30 days can use both recur:30days and recur:monthly, but a user in my situation doesn't have a solution.

It's not a big deal, every once in a while I just delete the recurrent task and create it again, but I would be happy to be able to do something like (in Y-M-D format)

task add Test task due:2015-01-05 recur:2months

and see my task created the fifth day of March, May, etc.

Is there a particular reason that I can't see to not implement this?