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.

Changes contributed by Manfred under https://github.com/eclipse/org.aspectj/pull/5/commits

- update to more recent JDT to pickup Nestmates fix
- bcel updated for NestMembers/NestHost attributes
- testcases for nestmates

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.

Took the code from the patch submitted by Mario Ivankovits
in bug 520597 and made some improvements to make (hopefully)
better use of memory. Some basic tests added.

On Java9 cannot rely on URLClassLoader being found from which
to determine classpath so use the environment variable. This may
have issues if loaders are being constructed that specifically
deviate from the java.class.path.

If you only let it determine it from the INVOKE instruction this
can make a mistake when using INVOKESTATIC with an interface
target.

Important to ensure we generate it of the right version as it may
end up containing code derived from a particular class that needs
a be run with a certain level of verifier. In this case if
inserting invokestatic targeting a interface method, we need to
be using something later than a java 1.2 level class file.