Fix sun size.
Merge branch 'master' into sunSize
Merge remote-tracking branch 'origin/master' into sunSize
Add a sunburst.
Get rid of sin() and cos() from sun shader.
Added get/setGlowFactor to address a feature request in #769.
Merge pull request #1081 from AnalyticalGraphicsInc/sunburst

Sunburst
Fix whitespace.
More whitespace.
Use Object.defineProperty for glowFactor.
Switch to Core/defineProperties.
Merge branch 'master' into sunSize
Merge branch 'master' into sunSize
Fix tests.
Make czm_solarRadius match CesiumMath.SOLAR_RADIUS
Render sun to texture then continue rendering the sun using texture lookup.
Update property definition per @mramato's review.
Fix build.
Fix sun glow.
Merge branch 'master' into sunSize

Conflicts:
	Source/Shaders/Builtin/Constants.glsl