improve UX when Omerta scrolls to top after page loads

- omerta.GUI.container.loadPageCB() is called whenever a page has been loaded.
  It will then scroll to the top of the page. This is usually a good idea,
  but can get quite annoying and feel sluggish when you're trying to train
  bodyguards as fast as humanly possible, and the game forces you to wait till
  the scrolling animation finishes before you can continue training.
  Instead, stop scrolling once the user tries to scroll at the same time.
rework OB preferences page

- use Omerta layout (resembles 'My Settings'-page)

- improve UX in some areas

- add more explanatory text to some settings that need clarification