OpenJFX 8 Backport to Java 7

[Danno Ferrin]

I've started a backport codebase for OpenJFX8 to Java 7.

https://bitbucket.org/narya/jfx78

The intent is to provide OpenJFX 8 code to Java 7 based VMs, whether it is
Oracle's JVM or other Java7 based VMs (such as RoboVM or Dalvik).  It's not
soup yet, it still needs some more open source libraries.  Right now the
compile breaks at the graphics module because the com.sun.javafx.accessible
packages have not been open sourced yet.

For the record I am only concerning myself with the gradle build and not
the current Ant based build.

Generally speaking the plans are to deal with the incompatibilities as
mechanically and predictably as possible.

* For lambdas expanding them to inner classes.  IntelliJ has a code
intention for this I am using
* For defender methods push down the default implementation to first line
implementors, giving it the same effect with more lines of code.
* For the new JSR-310 Date classes bring in the ThreeTen jars (
https://github.com/ThreeTen/threetenbp) (but it's not there yet)
* For java.util.function.Predicate<T> replace it with Callback<T, Boolean>

If anyone is interested in contributing and wants commit access, just ask.

--Danno