added SceneInterface::visibilityName = scene:visible
python binding for SceneInterface.visibilityName
Merge pull request #275 from davidsminor/sceneVisibleAttribute

added SceneInterface::visibilityName = scene:visible
Rewrote TestSceneCache to use parallel_reduce.

This fixes an issue where task.errors() was not returning a meaningful result. Now it returns the sum of all errors on all threads. I verified that without the fixes from 030e7c936de091e22564acec4bbffcb222154286 the test still gets the seg fault, and with those changes it passes.
Fixing seg fault when attempting to read a non-existant attribute several times.

This issue was introduced by 030e7c936de091e22564acec4bbffcb222154286
Merge pull request #277 from andrewkaufman/rootAttrCrash

 Fixing seg fault when attempting to read a non-existant attribute several times
Scene shape component names

Added an ensureComponentNames() method to FnSceneShape, for forcing the computation of the component names if the shape hasn't been drawn in the gl viewport. Also added component names unit test.
SceneShapeInterface::selectionName/componentNames() now automatically build the gl scene