- Speed up the child-handling of smart-ranges by using a binary search in the sorted child-list wherever possible, instead of iterating over all children.
- Use binary search in the renderer to find the next boundary.

This makes the whole smart-range stuff scale up a lot better up when there is many of them.

On my machine this speeds up the rendering in KDevelop-4 by magnitudes, finally it feels nearly like in KDE3.