Update Scaladoc comments.
Helper methods for executing code on JavaFX application thread synchronsusly - invoking thread is blocked till operation on JavaFX Application Thread completes, this is similar to Swing's `invokeAndWait`.

Based on blog post by Hendrik: "invokeAndWait for JavaFX"  http://www.guigarage.com/2013/01/invokeandwait-for-javafx/
Example of using `runAndWait` method.
Correct typos.