Use LambdaMetafactory instead of classic reflection whenever possible

[breitwan]

LambdaMetafactory 10% slower than a static MethodHandle but 80% faster than a non-static MethodHandle & Reflection

Replaced frequent reflection call to the constant field DEFAULT_PERMISSIONS by own constant Removed hacky use of sun.misc.Unsafe from LoginListener.java LMF is not used in one-shot things like LimboProtocol.java

https://stackoverflow.com/questions/19557829/faster-alternatives-to-javas-reflection/19563000#19563000 https://www.optaplanner.org/blog/2018/01/09/JavaReflectionButMuchFaster.html https://mail.openjdk.org/pipermail/mlvm-dev/2018-February/006817.html

[UserNugget]

Hello! Thanks for the PR, but maybe it is better to use VarHandle for current use case? It seems that VarHandle are properly optimized by the JIT compiler these days.

Edit: nevermind, VarHandle do not really has a proper way to modify final fields.

[UserNugget]

Thanks!