Type-ahead filtering for Projects and Outline panes

[humdingerb]

For larger projects it'd be quite handy to have Tracker-like type-ahead filtering. Then you could, for example, enter "window" and quickly see all the window related files (in a sanely naming project).

If you choose "Show in Projects browser" the type-ahead filtering there gets reset, if the target is currently hidden by an active filtering.

As in Tracker's filtering, a filter-term field left of the horizontal scrollbar is needed, reset with ESC.

[jackburton79]

Nice idea. Not sure how easy it would be, since the widget we use is the really basic BOutlineListView.
Anyway, since the ProjectBrowser looks like a filesystem tree view, I think it should work more like it. For example I'd also add the Canc shortcut to delete files