Merge pull request #17 from danman5555/master

[POSIX] Fix ConditionVariableImpl.cpp compilation errors.
Fixed crash caused by String class
Merge branch 'master' of https://github.com/DigitalPulseSoftware/NazaraEngine
Fixed OpenGL Renderer and Vendor names
Fixed rare crash within OpenGL::[GetRendererName|GetVendorName]
Fixed Matrix4::(Make)Ortho
Removed useless forward-declaration
Fixed Node::OnParenting callback not called
Added error detection
It is now possible to initialize VertexBuffer without VertexDeclaration
Fixed rare bug when creating VAO
Minor changes
Renderer::Clear now takes UInt32 instead of unsigned long
Fixed warning
Optimized WindowImpl::Get[Height|Position|Size|Width]
Improved error message
Added Window::OnWindowResized event
Fixed Matrix4::[Make]Ortho parameters name
Big Graphics update

Separated LightManager
Added Sprite class
Added View class
Camera is no longer a SceneNode
Fixed Material not invalidating programs
Renamed CameraPosition uniform to EyePosition
Renamed VisibilityTest to FrustumCull
Merge branch 'Graphics-Update'