#186 MacOSX: support for Java 9, 10, 11

[Makarius]

This is an update of the MacOSX plugin for Java 9, 10, 11 (build tested with Java 9 + 11 on Linux, but tested on macOS only with Java 11). See also:

• https://sourceforge.net/p/jedit/bugs/4068
• https://docs.oracle.com/javase/9/migrate/toc.htm#JSMIG-GUID-97C1D0BB-D5D3-4CAD-B17D-03A87A0AAF3B
• https://alvinalexander.com/source-code/java-macos-about-preferences-quit-handlers-desktop-awt