Shows trait properties/methods on class detail page

What's added to class details page:

1. show all traits that are used within a class in special "Traits" sub-section above "Properties" sub-section
2. show properties/methods that come from trait only if same property/methods doesn't exist in the class, which uses that trait (according to http://www.php.net/manual/en/language.oop5.traits.php#language.oop5.traits.precedence) 

![sami_showtraitsinclass](https://cloud.githubusercontent.com/assets/1277526/3417378/292f6cd8-fe38-11e3-955e-03e23d63a8b2.png)

I'm a bit unsure about the trait list design, because right now it's plain UL. Maybe it should be a table (like with properties) and in 1st column will be trait name and in 2nd column would be trait description (if any).

This PR implements item 1 from #78