[12] RFR: JDK-8198961: Remove old version of SceneBuilder from OpenJFX

[Kevin Rushforth]

Please review the following to remove the obsolete SceneBuilder sources 
from the openjfx/jfx-dev/rt repo:

https://bugs.openjdk.java.net/browse/JDK-8198961
http://cr.openjdk.java.net/~kcr/8198961/webrev.00/

Details of the proposed change are in JBS.

I will leave this review open for at least one week in case anyone wants 
to comment on this. As mentioned in JBS, the sources have not been 
touched since JDK 9, and then only to fix various Jigsaw issues.

The existing sources are still present in the openjfx/11-dev repo [1].

A fork of this repo is being maintained by Gluon [2].

-- Kevin

[1] 
http://hg.openjdk.java.net/openjfx/11-dev/rt/file/9a421b0a5ab1/apps/scenebuilder
[2] https://github.com/gluonhq/scenebuilder