Fixed wrong name of comparator and moved under the existent comparator package
Refactoring of Lock classes: moved under the existent lock package + created generic OLock interface to abstract locking in all other classes
Created new OListenerManager abstract class to make in common management of listeners
Minor: added copyrights header
client-server network improvements

This commit has many improvement on network part:
- fixed loose of network connection even after much time since
reconnection
- changed management of network connections: now is saved in TL also the
server URL, so on reconnection to another server the session ID is
reset to -1
- unreachable servers now are in the tail of server list
Replication conflict: changed message in case of auto-merge
Fixed issue with listeners on db.drop()