Improve caching of calledFromClass methods to avoid repeated calls to the classloader for classes not found

We faced a lot of threads beeing blocked by the synchronization in the UberClassloader. I extended the caching to use the complete stacktrace frame as cache key. That improved the performance on our Jenkins dramatically.

I also slightly improved the calledFromMethod call to have the getStackTrace() call only once for those three methods to check in InheritanceGovernor.