refactoring: extract caseinsensitive find_substr function
fix c++ command execution if Lua scripts has errors (earlier all c++ commands were ignored and it was not possible to run /lua rehash)
add logging feature for commands of each user https://github.com/HarpyWar/pvpgn/issues/47
correct commands code returns for properly logging https://github.com/HarpyWar/pvpgn/issues/47
Do not allow flood for admins due to possible abuse with quick command sending that high load a server processor. If we really need to ignore flood protection, it can be allowed in Lua config for special users https://github.com/HarpyWar/pvpgn/issues/49