Generate Timezone Options from Built-in PHP Function

[elchenberg]

I looked into this code because I got PHP warnings about undefined constants in setup.php. They were caused by non-breaking whitespaces near "Choose..." and "Europe/Copenhagen" () as I figured out later.

In the meantime, I decided to replace the original code with a loop that generates the drop-down list from the list of time zones provided by the built-in PHP function timezone_identifiers_list().