Runtime still throws warnings illegal actions even after all that, there's
just no logic to it. We can use Unsafe but don't touch setAccessible. O well
might as well enjoy Unsafe while we still can.

Wrapped the Unsafe and added method cache with varargs method for invoke calls.
Can still do a lot with it but it does what it needs to for now.

Wont stop you from getting an instance but it makes it more trouble at least.
Also reduce the visibility of the enum method.

The only thing remotely inforceable is caller class checking. You cannot
bypass an exception with setAccesible. Oracle went and removed
Reflection.getCallerClass() completely in favour of StackWalker. At least
we can share the SecurityManage ClassContext, SecurityActions seems the
appropriate venue for our stack trace peek to support the older versions

Java 7 and 8 does support method handles so we can cater for them. When doing
repeated invokes to the same method, keeping a reference to the Method handle
is much faster than reflection. Also the API is cleaner not having to Object[]
args etc. Worth the effort...

Remembered that 1.6 won't know about MethodHandles so must use reflection methods for them still.

Oracle (or maybe it was still Sun) warns that we should prevent from exposing access we gain to
privileged functionality like the unsafe etc. Before Oracle decides to restrict us even more lets
make an effort at least.