[O] Modify clock in/out time to previous/following full quarter of an hour.

[Rainer Stengele]

Hi!

My whole clocking is based on whole quarters of an hour.
When clocking in and out I always adjust the clocks to the previous or
the following quarter. I do not like to fiddle within minute-wise details.
Clocking in mostly is moved to the previous, clock out time to the
following full quarter.
I also do clock tasks mostly after the task is started for already a few
minutes.
I'd like to automatically push the clock-in time to the previous, the
clock out time to the following full quarter. This will save me many
times from manually adjusting two clock entries.

How could I achieve this? Which hook should I use? How? (I never
programmed something like this).

Thanks for hints,

Rainer