Styleable, StyleConverter and StyleOrigin wrapped.

Also was tried to wrap JavaFX classes CssMetaData, FontCssMetaData,
ParsedValue and StyleableProperty. However, their Specs tests did not
run correctly. Therefore I decided let them later.
Implemention of Styleable trait.

Classes which Java counterparts implements javafx.css.Styleables had
ScalaFX Styleable incorporated in their hierarchy  with the necessary
adjustments. Steleable's id and style methods were renamed to getId and
getStyle to not conflict with the methods with same name in their
implementaions.