- replace PHP4 style class constructor function names (based on
  class name) with php 5 __construct()
Also remove some '&' reference operators used with objects
And add some object type hints

The viewing options should only be visible on the first tab - which is
the installed Plugins tab. (There seems to be no more direct way to
address this tab.)

Since it is a JS function only, the form will be generated by it too.

Allows tho show/hide extensions that are: enabled, disabled, updatable

The user properties (login, real name, etc) where not properly escaped
in the user manager's edit form. This allowed a XSS attack on the
superuser by registered users.

Thanks to Filippo Cavallarin from www.segment.technology for discovering
this bug.