Fix V803 Decreased performance. In case 'it' is iterator it's more effective to use prefix form of increment.
    Replace iterator++ with ++iterator. stream_engine.cpp
    http://www.viva64.com/en/d/0165/print/
Fix V815 Decreased performance. Consider replacing the expression 'options.socks_proxy_address != ""' with '!options.socks_proxy_address.empty()'. session_base.cpp 497
Fix V815 Decreased performance. Consider replacing the expression 'peer_address = ""' with 'peer_address.clear()'. stream_engine.cpp 99
Merge pull request #1202 from pavel-pimenov/fix-pvs-studio

PVS Studio small fix