Fix #1548
replace functions
replace functions in code
check sandcastle, update CHANGES.md
doc cleanup
Expose `DataSourceDisplay.defaultVisualizersCallback`.

This allows applications to install new visualizers globally, since Viewer doesn't currently provide a way to customize them on a per-DataSourceDisplay level.
Merge pull request #1576 from AnalyticalGraphicsInc/dataSourceDisplayVisualizers

Expose `DataSourceDisplay.defaultVisualizersCallback`.
cleanup
Fix a few typos.
Merge branch 'master' into replaceGetSetRenderer

Conflicts:
	CHANGES.md
	Source/Renderer/Framebuffer.js
	Source/Renderer/ShaderProgram.js
	Source/Renderer/Texture.js
	Source/Scene/TexturePool.js
	Specs/Scene/TexturePoolSpec.js
functions to properties
default sampler undefined
Merge pull request #1574 from AnalyticalGraphicsInc/replaceGetSetRenderer

Replace get/set functions with properties : Renderer
replace functions in code
Merge branch 'master' into replaceGetSetUniformState
functions to attributes
Merge pull request #1579 from AnalyticalGraphicsInc/replaceGetSetUniformState

Replace get/set functions with properties : UniformState
replace functions in code
sandcastle
Merge branch 'master' into replaceGetSetContext