Fixed overlapping lines.
Fixed overlapping lines.

There were some overlapping lines caused by a round off error in the method "centerStairsInPathPoints".


Former-commit-id: c0efcb93044c68e08cfe8b9c6702e2820b3ef3f4
webgme/webgme-engine,webgme/webgme-engine,webgme/webgme-engine