Bump for 1.6.6

Fix JRUBY-6383

Scala integration breaks with 1.6.6

This has actually been "broken" since 1.6.0, since we were not
defining the symbolic names for any of the $ Scala methods. This
fix adds the symbolic names and leaves the originals intact.

Update to reflect 1.6.5.1

Modified fix for Pull Request jruby#85 jruby#85

Fix compiler for new DNode logic

Bump for release

Bump for 1.6.2

Set tag for 1.6.1.

Bump versions for final 1.6.0 release

Bump for RC3