[PATCH] Prefer new node when selecting after unglue

[robome]

I and judging from a thread on the talk-de would prefer if after ungluing ways a node select would pick the new node (id 0) instead of the old ones.

The attached patch does that.
In it I've also taken the liberty to add minor tweaks which may improve performance by one or two nanoseconds. Also I find the compares better comprehensible the new way.

[robome]

Select path

[stoecker]

In r1497. Changed a lot.