Release v1.1.0

This is the 1.1.0 release of Spectrum for both Android and iOS. These are the major changes included:

• Spectrum now supports modular headers when using cocoapods
• Spectrum now supports setting the compression level for libpng (see dabe878)
• Spectrum now supports setting a custom SoLoader implementation (see 1fbd80e)
• Fixed Spectrum's PNG encode operations from ARGB input (see 4d9ed16)
• Spectrum's dependency on libwebp is updated to 1.0.2 (see 548c81e)
• Spectrum has experimental support for decoding AV1 frames in IVF containers (see 52868e3, 429aeed, c46d7c8 and 16ed05a)
• Improved documentation including highlights of Kotlin/Swift interoperability
• Various fixes and improvements

Big thanks to @lambdapioneer , @cuva, @morozkin, Wenbin Zhang , @wakwak3125, @EwoutH and @tatocaster for the contributions! 😍