Bugfix release:

* [OpenGL] Add support for RG8 textures
* [OpenGL] Support nonperspective interpolation on GLES hosts 
* [OpenGL] Improve support for texture shadow LOD 
* [Vulkan] enable support for more extensions 
* [Video] Add support for H264 and  H265 video encoding 
* Enable the use of external objects for AMDGPU based hosts 
* Fix caching type for llvmpipe based hosts thereby enabling blob resources
* Fix a series of errors reported by static analysis and other bugs (see git log)