Hi,

This patch introduces an user option to conditionally include
world-clock time, in addition to the localtime, when display-time-mode is
active, in mode line. Right now time in different timezones is only
available in a separate world-clock buffer, having this information
included in the mode line would be useful in my book. WDYT?

I'm not sure if I already have assigned copyright to the FSF before,
so I'll do that within the next hours as required.