TrueVFS 0.13.0

In this version the main code has been translated back from Scala 2.X to Java 8. This significantly reduces test time (no more cross building and integration testing the code with four different versions of the Scala library) and ongoing maintenance effort. It also rids end users from an unsolicited dependency on the Scala library and therefore simplifies adding TrueVFS libraries as dependencies (no more kernel-impl_2.13 dependency required).

There have also been stability improvements. Previous spurious exceptions in heavily contended multi-threaded environments are now gone (this was not the fault of the Scala library).

Scala 2.13 continues to be used for the test code because of its unmatched conciseness.