caching of call results is currently disabled

[mattja]

Currently caching relies on the id() of the proxy object as part of the key for storing cached results.
This is wrong, as the id is only guaranteed to be unique among objects existing at the same time.

Result: If a proxy object is deleted and later another proxy with the same interface happens to be created at the same address in memory (not unlikely) then the new proxy may return cached results that belong to the old proxy.

Solution: Instead of a global cache, have one cache instance per proxy, with only the total memory usage managed globally

[mattja]

Disabling method result caching globally until I have time to do this properly.