darcs patch: Figure out timezone offset from timezone name

[Isaac Dupree]

Bjorn Bringert wrote:
> - The timezone table is rather long, and uses plain 'lookup'. OTOH,
> introducing a dependency on the 'containers' package seems excessive
> just to do faster lookup.

it doesn't seem excessive to me -- one of the main things 'containers' 
implements is fast(ish) lookup.  But you mean the way it's looking up 
amongst a fixed/hard-coded set of keys?

-Isaac