Fix initial geometry outline color.
Remove need to explicitely set depthTest for geometry outlines.

We already compute the correct value automatically in `Appearance.getDefaultRenderState`. This change updates `Appearance.getDefaultRenderState` to apply unset defaults to the specified user options and remove the explicit settings throughout the code.
Merge pull request #2284 from AnalyticalGraphicsInc/outline-cleanup

Remove need to explicitely set depthTest for geometry outlines.