Update 1.2.34

• Switch mixin implementation to fabric fork of sponge mixins
  (Should make mod mixins work be more reliably and work as expected more often)
• Extracted fallback subproject into it's own project, called JFallback.
• Made dev plugin support java8 again to help new developer using the plugin.
  (While VineFlower require java 11, it will run fine through JFallback compatibility layer)
• Add server side hotfix that could prevent player from loggin in.
  (Note: This fix an issues with reindev itself, without FoxLoader the bug will still occur)
• Fixed lua API, so now it now can call java code as if it was lua code
• Add more error messages when duplicate mixins data is detected
• Slightly optimize memory usage of the main class loader
• Fixed typo in world editing commands