- add the use of DRWShaderLibrary to EEVEE's glsl codebase to reduce code complexity and duplication. - split bsdf_common_lib.glsl into multiple sub library which are now shared with other engines. - the surface shader code is now more organised and have its own files. - change default world to use a material nodetree and make lookdev shader more clear. Reviewed By: jbakker Differential Revision: https://developer.blender.org/D8306