MC-Repack 0.20.0

Big version bump for big changes:

• NEW NBT optimizer!
• Using Zopfli where possible (currently as a core feature, not in CLI)
• Reading config from mc-repack.toml file (or one specified by --config option)
• Configurable minifiers (JSON, TOML, Zopfli when available)
• Optimized required file size limits for Store instead of Deflate
• Fix: Remove .cache/ properly
• Breaking change: Deprecate optimize_archive and optimize_fs_copy

And many more!
Full Changelog: v0.18.1...v0.20.0