Version 5.0.0-BETA01

This is the first beta release of the 5.0.0 SPIO plugin. Please do not use this version in production, yet!. Among the various changes and fixes:

• the optimization metadata is now stored in a separate place (still in the wp_postmeta table), in order to avoid the issues with other plugins wiping out ShortPixel optimization information (which was resulting in re-optimizing images); a migration tool has been added, which will copy all the existing data to the new format (old data is still preserved);
• completely reshaped Bulk Screen, it now has multiple steps with a much cleaner interface and better overview of the process and progress;
• AVIF/WebP files can be generated separately for already optimized images;
• a new "Tools" tab has been added with some useful tools;
• lots of other bug fixes and small improvements with regards to various parts of the plugin.