Implement new threads design

Implemented the new design and layout for the threads tab.
This includes all of the new functionality, like filtering the thread list using a handy search bar, different areas for selected an unselected thread etc...

On top of that, in order to enable such behavior, I changed the threads list view to update partially only the areas in the DOM that require updating. This makes the rendering considerably faster, and allows a more "smooth" usage, without the scrollbar jumping up and down every second.