groundwork for KIL to KORE conversion

skeloton for unit testing and some necessary Scala - Java interop
small fixes
a few more baby steps
wip
fix sbt maven plugin version
working for basix syntax with attributes

Conflicts:
	kore/src/main/scala/org/kframework/kore/helpers.scala
abstract `map` better
implementing missing pieces. minor refactoring.
minor refactoring
WIP: trying to make user lists working
refactor file reading
implement some TODOs in Interface and converter.
override NonTerminal toString method
fix userList test
minor refactoring
fix compilation errors
syntax priority options
Merge remote-tracking branch 'origin/master' into feature/KORE-convertors
fix checkstyle issues
new test files