* Consistent single quotes

* Consistent single quotes
* The problem with onKeyUp was that is shows errors even when initially typing a (possibly valid) address. onBlur has the downside of not giving feedback while correcting the mistake + since e-mail is the last input element at the moment, it doesn't blur on submit and required a seperate event handler.
** Solution: Bind onBlur once, and then listen for onKeyUp.
* Adding missing semicolon(s)
* Compare with strict (===) to empty string / null
* Moved non-global wfFunction to mw.util
** The "FIXME:" note was kept
* Comment "apostrophe" fixed to "at". Comments don't run :)
* Caching selector in wfUpdateMailValidityLabel
* Renaming "wfUpdateMailValidityLabel" to "updateMailValidityLabel"
( Ping r79910, r75670, r75627  )