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 ensures there will be at most one copy of the stage, which will be
created and destroyed as needed. Trying to create a second just brings
the first into focus. This is good for things like preferences windows.
Rohan Sircar
Sarah Gerweck