Release Candidate for OpenPBR v1.0

Added

• Add coat darkening and saturation effects by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/162
• Define Oren-Nayar lobe explicitly as EON model (i.e. energy-compensated Fujii) by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/174
• Specify the anisotropy direction by @virtualzavie in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/170
• Coat roughening convolution formula by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/172
• Add a discussion/solution of the coat "spurious TIR" issue by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/166
• Add white furnace testing section by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/192

Changed

• Thin-film improvements by @portsmouth in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/167
• Remove Future work notes and left over comments by @virtualzavie in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/181
• Rework readme links by @virtualzavie in https://github.com/AcademySoftwareFoundation/OpenPBR/pull/182