Fix navbar scroll with toc.

Looks like doxygen's navtree js has changed, requiring us to change our override hacks to resize the navbar to fit our TOC. Because the resizeHeight function is now privately nested in another function, we need to override the entire outer initResizable().

Also requires adjusting the position - the absolute position for div.toc seems to interfere with scrollbars.

Fixes #2467 (closed)