Cleanup buildscripts, tests, and benchmarks

[solonovamax]

Cleans up buildscripts, tests, and benchmarks

• Add nyx gradle plugin
• Enable publishing of javadoc & sources jar
• Add solo-studios maven repo (can be removed if desired)
• Update benchmarks
  • Test additional expressions
  • Use longer test time for more reliable results
  • Update README with new benchmark run
• Upgrade to JUnit 5

Fixes #9