kawa 3.x transition

[Per Bothner]

In the next week or two I plan to:

- Make a final 2.4 release from the master branch, and tag it.
- Change the version number of the invoke branch to 2.92.
- Merge the invoke branch into master.
- Change the default for both the git sources and binary releases to Java 8.
(Java 6 and Java 7 will be supported, but will require building from source.)

Does anyone see any problems, or last-minute things to get into 2.4?
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/