* GCC support - could be used via -PuseGcc command line argument.
* Refactoring around __FUNCTION__, change __FUNCTION__ into __func__.
* Refactoring, formatting, small fixes.
* Fixed "error C4996: 'GetVersionExA': was declared deprecated" using a crutch.
* Added NOXREFCHECK to all NOXREF functions.
* Removed NOXREF from Sys_CheckOSVersion because it is being called.