changed unity3d to 7d2d specific logs
Script now detects 0x402 error on SteamCMD

https://github.com/dgibbs64/linuxgameservers/issues/235
Created fn_syscheck
Created fn_messages
Created fn_functions

This moves all the defining functions to its own file and out of the
main script file. This has made the main scrip file much smaller and
moved most code to the functions dir