Fixed a bug affecting the animation of the opacity property
DKS - added automated test for drawLinesInstantShiftVariedOpacity().
Merge branch 'master' of https://github.com/caleb531/jcanvas
DKS - added a 1ms duration to the animateLayer_twoAddsTwoAnimates test.  Not sure why that's required (other tests succeed at 0ms), but not worried about it right now.