Merge pull request #318 from fraenke75/RequestHandlers

Added CefRequestHandler.OnBeforePluginLoad
Move the documentation to IRequestHandler. With a fix to info on return value - which also matches CEF API doc :)
Polish OnBeforePluginLoad handler example code a bit.
For safety towards side effects in old code keep it disabled for now though.
Huh - my keyboard has side-effects. Must be a hardware error :P