[Orgmode] Set timestamp duration

[Nuutti Kotivuori]

Hi,

I'd like an easy way to set the duration of an appointment (a
timestamp) after it has been created.

Something like a keybind prompting for a duration (in hours and
minutes or some wiser parser) and then converting the timestamp at
point to have a start time and an end time.

Again, if somebody else sees this useful as well, please chime in,
otherwise I'll just hack it for myself.

Sorry, no keybinding suggestions yet - I'm not too savvy on everything
org-mode has to offer.

-- Naked