- Disable Visual Mode view stretching
- Disable increased texture brightness in classic modes
- Increased default Visual Mode FOV from 80 to 90

The calls to native windows functions wouldn't be valid on any unix os
so expand the check.

The check for Windows XP is removed as that platform is not supported
anymore.

When saving a wad for the second time some code would run that tried to
use native windows function and caused a crash.