[+BUGFIX] AOP: Fix proxy initialization in inherited proxyclasses
This adds a check to the proxy classes constructor method
to initialize aop functionality only for the actual
instantiated class and not for its parent classes.
Besides that it is now possible to set the visibility of a proxy
method. By that FLOW3_AOP_Proxy_buildMethodsAndAdvicesArray(),
FLOW3_AOP_Proxy_getAdviceChains() and FLOW3_Proxy_injectProperties()
are now private as they should be.