Object pooling proxy implementation.

The `org.apache.commons.pool2.proxy` package defines a object pool that wraps all objects returned to clients. This allows it to disable those proxies when the objects are returned thereby enabling the continued use of those objects by clients to be detected..

Support is provided for `java.lang.reflect.Proxy` and for `net.sf.cglib.proxy` based proxies. The latter, requires the additional of the optional Code Generation Library (GCLib).