Remove useless include files and part of code too
Move defines Q_* functions from engine/common.h to public/strtools.h
Rename functions:
strcopy > Q_strlcpy
strncopy > Q_strnlcpy
* GCC support - could be used via -PuseGcc command line argument.
* Refactoring around __FUNCTION__, change __FUNCTION__ into __func__.
* Refactoring, formatting, small fixes.