Based on analysis from the visualization of
the router, the code has been rewritten to
speed up the routing during multi-tap (more
than 2 connections) nets, so that previous
search results remain in place after each
route, avoiding redundant searching. This
speeds up qrouter by a factor of about 2x.
A masking function that limits routes
to a specific defined portion of the layout
speeds up qrouter by a factor of about 30x.