Updates to better cope with future JDKs

Updates to better cope with future JDKs

The version handling in LangUtil has been overhauled
to cope better with post 1.8 releases (JDK9 and JDK10 or 18.3
or whatever they call it). As part of this moved
to treating JDK9 as '9' rather than '1.9'. Also removed
duplicate version processing logic and had that defer to
the one place in LangUtil where we now deal with it.

Includes some generics tidyup in ajdoc. More ajdoc work
is necessary for Java10 because it removes the standard doclet
(old style). However trying to invoke the internal Javadoc
handler in Java10 is failing due to module visibility rules.