[RFC|Merged] Switch to PHP timezone handling

[EXreaction]

Reported

[naderman]

Thank you!

[sajaki]

Before, only the UTC timezone was shown. now, it is the GMT zone and then a long list of continent/city combinations belonging to that timezone.

before

in v3.1-dev.

I think it's better to keep the Coordinated Universal Time (UTC) according to ISO 8601.

[nickvergessen]

When javascript is enabled the box can be limited to a certain time.
The problem with the old UTC stuff was, that it did not include dst (daylight saving time) requiring european users and more, to switch it on and off every 6 months and the problem is, that it can be individually set by each country.

This information is already included in the new timezones and so teh user selects his timezone once and then has never to touch the setting again, until he/she moves to a different timezone.