Clarify notes on drawing dynamic textures during context loss.
Allow `Shader` to initialize and operate during context loss.
Improve resize handling on context loss and recovery.
All textures and shaders should automatically recover from WebGL
context loss.
Dynamic textures will lose their contents, unfortunately, as the texture
was stored on the GPU.
Frame buffers still have some bugs to work out.
This is mostly hooking up gl calls to look inside the wrapper.
A few other things have changed.
Spector metadata is set the new way.
`Frame` changed `glTexture` to a getter, simplifying bookkeeping.
`LightPipeline` and `Plane` use standard methods to create textures.
`WebGLRenderer` maintains a list of wrappers, and automatically
manages it through `createTexture2D` and `deleteTexture`. The update
methods `updateCanvasTexture` and `updateVideoTexture` have been
delegated to the wrapper.
* The `WebGLRenderer.currentActiveTexture` property has been removed.
* The `WebGLRenderer.startActiveTexture` property has been removed.
* The `WebGLRenderer.tempTextures` property has been removed.
* The `WebGLRenderer.textureZero` property has been removed.
* The `WebGLRenderer.normalTexture` property has been removed.
* The `WebGLRenderer.textueFlush` property has been removed.
* The `WebGLRenderer.isTextureClean` property has been removed.
* The `WebGLRenderer.setBlankTexture` method has been removed.
* The `WebGLRenderer.setTextureSource` method has been removed.
* The `WebGLRenderer.isNewNormalMap` method has been removed.
* The `WebGLRenderer.setTextureZero` method has been removed.
* The `WebGLRenderer.clearTextureZero` method has been removed.
* The `WebGLRenderer.setNormalMap` method has been removed.
* The `WebGLRenderer.clearNormalMap` method has been removed.
* The `WebGLRenderer.unbindTextures` method has been removed.
* The `WebGLRenderer.resetTextures` method has been removed.
* The `WebGLRenderer.setTexture2D` method has been removed.
* The `WebGLRenderer.pushFramebuffer` method has had the `resetTextures` argument removed.
* The `WebGLRenderer.setFramebuffer` method has had the `resetTextures` argument removed.
* The `WebGLRenderer.popFramebuffer` method has had the `resetTextures` argument removed.
* The `WebGLRenderer.deleteTexture` method has had the `reset` argument removed.
* The `WebGLRenderer` has 4 new properties: `maskTargetFramebuffer`, `maskSourceFramebuffer`, `maskTargetTexture` and `maskSourceTexture`. These are the new global locations of the mask framebuffers.
* `WebGLRenderer.createBitmapMask` is a new method that internally creates the Bitmap Mask framebuffers.
* `WebGLRenderer.clearBitmapMask` is a new method that internally clears the existing Bitmap Mask framebuffers, called as part of a resize event.
* `WebGLRenderer.enableBitmapMask` is a new method that starts the process of using the mask target framebuffer for drawing. This is called by the `BitmapMaskPipeline`.
* `WebGLRenderer.drawBitmapMask` is a new method that completes the process of rendering using the mask target framebuffer. This is called by the `BitmapMaskPipeline`.
