Continue of previous commit.
* add help description for /mail and /ipban https://github.com/HarpyWar/pvpgn/issues/5
* refactoring: move /icon command to icons.cpp, move split_command() to common
Improvements for commands:
/lock <player> [hours] [reason]
/mute <player> [hours] [reason]

https://github.com/HarpyWar/pvpgn/issues/3