Feature request: make at command more intelligent

Hi,

The current at command is relatively strict in what it accepts as a parameter. I think it would be nice if it could accept things like this - maybe with a new command "on":

khal on 11 - where it guesses the day is the 11th khal on tomorrow - self-explanatory khal on tomorrow+1, +2, +3, - day after tomorrow, day after that, etc.

Or maybe also:

khal in mar - show events in March etc.

I realise creating this software means a lot of work for the developer - so, first of all, many thanks for doing this. It really helps me in day-to-day's work. Second, I am happy to take a stab at this myself soonish if you're OK with it?