Download and install a clean eclipse-jee-2019-06

In gradle.properties edit `jalviewjs_eclipse_root` to point to the root dir. DO NOT include the Eclipse.app folder in the path (up to this point, but not the .app folder) if it's the macOS version.


gradle tasks of interest:

`jalviewjs` (should do everything)

jalviewjsTranspile (should run a new eclipse compile+transpile)