Monitor: Added printing error message when monitor initialization is failed.
Tests: added generating monitor ports.
Pytests: Turn off pytest recurse discover for tests.
Log: removed duplicating log from monitor.cpp. Added dnet_log_raw_log_only and dnet_log_raw_internal. Made dnet_log_raw to use dnet_log_raw_internal.
Session: added checking groups list for emptiness at iterator operation.
Merge pull request #394 from shaitan/master

Tests and Monitor (Master)