Support for date segment to take a timezone argument

[shawncplus]

I wanted the functionally to have two clocks of different timezones in my powerline, this did the trick.

[ZyX-I]

You should make this optional.

[shawncplus]

Are you saying making the feature altogether optional if they have pytz installed? That makes sense.

[shawncplus]

I have no idea if I did the optional bits correctly but it seems work correctly with pytz installed and not and raises proper errors when trying to use unavailable functionality

[ZyX-I]

You should not use parenthesis here.

[PH111P]

While I like the idea of the time segment taking an optional timezone parameter, I'm not quite convinced by the implementation presented here:

• Another package is required for functionality that should be easily doable with vanilla python. In particular, specifying the timezone as +HHMM or -HHMM would allow the use of strptime (%z).
• The fuzzy_time segment should also get timezone support (this should be a minor issue though)
• I find calling the additional parameter tz not optimal; better would be something more intuitive like timezone