Docs for CurveNode.getPtOnCurve() and .length

git-svn-id: https://www.libavg.de/svn/trunk/libavg@9290 44470bb9-56e9-0310-a0f8-c586564d3dc6
Minor doc fix.

git-svn-id: https://www.libavg.de/svn/trunk/libavg@9291 44470bb9-56e9-0310-a0f8-c586564d3dc6