Use fastutil-core or include only needed fastutil classes

[Marcono1234]

The fastutil dependency is currently ~20 MB large, however this project only uses a small fraction of the available classes. It might therefore be worth investigating whether it is possible to reduce this memory usage:

• Using fastutil-core
fastutil-core only includes a fraction of all classes available in the regular fastutil artifact. However, it has these problems:
  • It might not contain the classes needed by this project
  • Because it contains the same classes as the regular fastutil artifact, it could lead to issues for consuming projects when they have both dependencies on their classpath (and tiny-lingua cannot do much / anything to prevent this).
• Shading the needed classes from fastutil into tiny-lingua
  • Have to check whether the fastutil license permits this, and whether that makes licensing / distributing tiny-lingua more difficult
  • Maintaining the list of classes to include / exclude will be error-prone