Update to latest release of richtextfx (#4213)
Update to latest release of richtextfx (#4213)

RichTextFX will no longer be maintained
https://github.com/FXMisc/RichTextFX/issues/768
zellerdev/jabref,sauliusg/jabref,zellerdev/jabref,Siedlerchr/jabref,zellerdev/jabref,Siedlerchr/jabref,JabRef/jabref,sauliusg/jabref,JabRef/jabref,JabRef/jabref,Siedlerchr/jabref,Siedlerchr/jabref,zellerdev/jabref,zellerdev/jabref,sauliusg/jabref,JabRef/jabref,sauliusg/jabref