Full frontal ClassLoader nudity.

 Support loading Gosu classes/types by source in _multiple_ ClassLoaders i.e. ,the entire chain.  Before this change we used to load Gosu classes from source in a single ClassLoader.  In a normal non-GW application this is typically Java's AppClassLoader.  In a GW app it would be a PluginContainer loader.  The problem with this is that Gosu classes may not load in the class loader corresponding with where they exist on disk.  For instance, a Gosu enhancment loaded from source would load in the PluginContainer even though it's defined inside a package not meant to be loaded by the PluginContainer.  Similarly Gosu test classes defined in a the test source path would load in the PluginContainer, which would make them not capable of sharing package-level access to Java classes declared in the same package, which is very inconvenient for writing tests.

  Now with this change Gosu classes are guaranteed (or your money back) to load in the same ClassLoader as Java classes declared alongside them.  This also alleviates long standing issues dealing with Gosu class (loading from source) involving having to set the Thread's context loader.  Now there should be no difference between Java or Gosu in that regard.

  The visible difference you'll see is an additional path added to each ClassLoader in the class loader chain (see changes in GosuClassPathThing).  Basically Gosu dynamically adds its "gosuclass://" protocol as it used to, but now instead of the "gosuclass://honeybadger/" hosted entry we add an entry with a host encoded with the address of each ClassLoader e.g., "gosuclass://1234567890/", as we walk the chain.  Then in the process of loading a class our URL handler finds the ClassLoader corresponding with the host of the URL and then determines if the Gosu source file associated with the class identified in the URL's path is in that ClassLoader's paths via findResource().  If so, we load the class in that loader, otherwise we let the loader chain proceed with loading until we find match or the class is not found (see changes in GosuClassUrlConnection).