Added `Scene.drillPick` for picking of multiple primitives
handle multiple ways of hiding primitives
changed test to check if setShow function is defined
fixed doc comment
Merge branch 'master' of https://github.com/gbeatty/cesium into multiPicking

Conflicts:
	CHANGES.md
	Source/Scene/Scene.js
first pass
working polyline volume
Merge branch 'master' into multiPicking

Conflicts:
	CHANGES.md
cleanup formatting
completed outline
sandcastle example, web workers
Merge branch 'master' into polylineVolume
specs
formatting
height WIP
fixed bad merge
code cleanup
sandcastle drill-down picking example
initial support for geometries
removed unused require