addressed Dwight's feedback
move Collections
import
move Collections to org.kframework.
Java-8-style interfaces for collections
formatting
move to right source folder
checkstyle
cleanup and an extra test
more tests
checkstyle fix
manipulating a KList
some fixes and more examples
Merge branch 'feature/generic-collection-interfaces'

Conflicts:
	kore/src/main/scala/org/kframework/collections.scala
	kore/src/main/scala/org/kframework/kore/AssocBuilder.scala
	kore/src/main/scala/org/kframework/kore/Collections.scala
	kore/src/main/scala/org/kframework/kore/kast.scala