Added default parameters to vignette

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branch : feature/posteffects
Added pc.posteffect.PostEffectQueue for managing multiple post effects for a camera. The camera component now has a post effects queue allowing users to add / remove post effects to a camera.

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branch : feature/posteffects
Added addEffect method which got deleted before the commit

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branch : feature/posteffects
Create separate depth target for post effects that need one, Added bokeh2 effect (not working right)

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branch : feature/posteffects
Added example using post effects

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branch : feature/posteffects
Clean up memory when various render targets are not needed anymore

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branch : feature/posteffects
Added color correction post effect

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branch : feature/posteffects
Added brightness contrast post effect

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branch : feature/posteffects
Added horizontal tilt shift post effect

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branch : feature/posteffects
Fixed horizontal tilt shift with focus parameter

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branch : feature/posteffects
Fixed bug in horizontaltiltshift

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branch : feature/posteffects
Added vertical tilt shift post effect

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branch : feature/posteffects
Added hue saturation post effect

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branch : feature/posteffects
Added comments with original authors of post effects

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branch : feature/posteffects
Merge from default

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branch : feature/posteffects
Call Component#onEnable after a component is initialized

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branch : feature/multiple-cameras
Camera system now has an array of active cameras instead of a 'current' camera. The application framework now renders all cameras instead of just the current camera.

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branch : feature/multiple-cameras
Removed some outdated comments

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branch : feature/multiple-cameras
Removed references to removed CameraComponentSystem#current

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branch : feature/multiple-cameras
Exposed priority, clearColorBuffer, clearDepthBuffer and rect for the camera component, Now supporting pc.Vec2 and pc.Vec4 as runtime types

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branch : feature/multiple-cameras