Code optimisations for timezone dropdown builder.

[sambauers]

The new timezone dropdown builds noticeably slowly in 2.8 causing lag when opening the general options page in admin.

The main problem was with inefficient use of translate functions within the usort callback.

Secondarily, the loop which builds the actual options html was using a string concatenation method which pulls and pushes the same variable in and out of memory hundreds of times.

The following patch fixes both of these problems and generally tidies things up. Performance is improved noticeably.

Haven't looked the whole patch over yet, but __() can accept only literal strings. translate() should be used if passing a variable or function return.

Replying to ryan:

Haven't looked the whole patch over yet, but __() can accept only literal strings. translate() should be used if passing a variable or function return.

I'll fix this and resubmit the patch.

Re-uploaded patch with that fix plus one other.

Removes NBSPs padding for timezone cities. See ticket #10206

See #10210

(In [11597]) Optimize timezone dropdown creation. Props sambauers. fixes #10125 for trunk

(In [11598]) Optimize timezone dropdown creation. Props sambauers. fixes #10125 for 2.8.1