Updated scala version to 2.13.4
Compiles to Java 11 now
Updated sbt to 1.4.3
Updated scalafx version to 14
Removed unneeded dependencies
Removed Akka code
Added lint and fatal warnings scalac options
Added parantheses to side effecting methods
Added >> and << methods to observables
This was never actually used, except maybe in an experimental branch.
Akka Agent is officially deprecated so I won't be adding any ScalaFX
bridges for it. Use actors to manage state instead.