Uniform gIsPlaying indicating if the player is running in the glsl code
Glsl downsampling code deactivated while playing to keep a good frame rate on lower end machine
color conversion function corrected
AlexaLogC colorspace
Use only a few format from OpenImageIO
Merge remote branch 'upstream/develop' into primefocus

Conflicts:
	src/duke/engine/rendering/GeometryRenderer.cpp
	src/duke/engine/rendering/GlyphRenderer.cpp
	src/duke/engine/rendering/ShaderConstants.cpp
	src/duke/engine/rendering/ShaderConstants.hpp
	src/duke/engine/rendering/ShaderFactory.cpp
cstddef include added for size_t definition
removed gIsPlaying variable
default colorspaces for exrs and jpegs
changed "missing frame" message to "caching" which is more appropriate from an user viewpoint
comments similar to mikros repository
comments similar to mikros
refactoring: moved colorspace related functions in a new file ColorSpace.cpp
new command line arguments : --inputspace and --outputspace to force the input and display colorspaces
now duke manage a file colorspace and a screen colorspace instead of a unique colorspace. It was not clear what the unique colorspace was refering to.
pass the colorspace command line arguments to the context.
Also added a test code to render only when the buffer is available, it will surely be removed in the next commits
Merge remote branch 'upstream/develop' into primefocus

Conflicts:
	src/duke/memory/AvailableMemory.hpp
rec709 color conversion functions
read pixel ratio in dpx files
glsl bilinear and nearest neighbour filters
AlexaLogC to linear function is now correct