Add stylecheck SBT plugin setup.
Code style corrections.
Correct use of parathensis after chages to ScalaFX API.
Code style corrections.
Use M5-SMAPSHOT for development.
Simplify code after ScalaFX Issue 66 (Wrapper classes should not be `final`) was fixed.
Simplify code after ScalaFX Issue 67 was fixed (simplify handling of Runnable).