More testcases for overweaving and better handling of WeaverStateInfo
to avoid the dreaded problems deserialized the 'special key' used
to store diffs.

With these changes once a class is woven via overweaving we switch
the diff we store in the weaverstateinfo to 0 byte array (indicating
overweaving happened for later weavers that see it). We also stop
writing the special 'key' into the attribute and avoid looking-for
and attempting to replace it at the end of weaving.

The existing check crudely only checked the top level, failing
to find nested WildTypePatterns.

Resolves #542682

In this version unless you specify an aspect is privileged then the
pertypewithin clause will not match types not visible from the aspect
(private types or default vis types in another package)

Debating whether to change this to not require privileged.

This commit introduces some new methods into the
runtime Factory class and modifies code generation
to use them (and to use the form of the LDC bytecode
that loads class constants).

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.

Compile error: ClassCastException thrown: org.aspectj.weaver.MissingResolvedTypeWithKnownSignature cannot be cast to ReferenceType

Multiple changes here:
- annotation unpacking is smarter and if it only needs runtime
  retention annotations it uses reflection and doesn't unpack the
  bytes to discover class level retention annotations.
- Reflection worlds are shared if for the same classloader.

I don't want to change that code until I see more evidence of it
misbehaving but I'm having trouble working out why it is there!