This changes core routing so that '<path..>' in a route URI matches zero
or more segments. Previously, '<path..>' matched _1_ or more.
* Routes '$a' and '$b/<p..>' collide if $a and $b previously collided.
* For example, '/' now collides with '/<p..>'.
* Request '$a' matches route '$b/<p..>' if $a previously matched $b.
* For example, request '/' matches route '/<p..>'.
Resolves#985.