Allowing half hour Timezone offset

[I had submitted this to the -devel ML. But I am adding this here too so that people with similar problem to mine can use the solution]

I am from India, where the timezone (IST) is GMT + 0530. Drupal currently
doesn't allow me to specify my exact timezone because the zone options are in
multiples of an hour.

My patch (at http://www.sandipb.net/drupal/zonepatch) to the user module should cause drupal to show zone options
with half an hour interval, and to display zones in the normal manner(+/-
zero-padded hour,zero-padded minute offsets).

- Sandip