c: Add missing cleanup code in ipcon_connect_unlocked
python: Don't use callback lock for now

Could deadlock due to an lock ordering problem with the socket lock.
c: Don't use callback mutex for now

Could deadlock due to an mutex ordering problem with the socket mutex.
java: Remove debug output
java: Don't use callback mutex for now

Could deadlock due to an mutex ordering problem with the socket mutex.
ruby: First try to fix callback dispatch stopping on disconnect

Callbacks could still get dispatched while the socket was already closed.
This resulted in a guaranteed timeout exception for getters called from
callback functions.

Try to use an additional lock to serialize disconnection and callback
dispatch. But the problem is, this could deadlock due to an mutex ordering
problem with the socket mutex.