Win: Add IS_WIN8PLUS macro and disable DW_FCF_COMPOSITION for Windows 8 and higher. The method used in Vista and Windows 7 to control what is drawn as glass has adverse side effects on Windows 8 and 10. Mouse clicks on what would be "glass" passed through to underlying windows due to the use of LWA_COLORKEY to specify transparency color. Additionally the glass effect has been removed. Glass was the main reason for implementing DW_FCF_COMPOSITION so just ignore the flag on Windows 8 and higher. https://stackoverflow.com/questions/4768862/dwmextendframeintoclientarea-without-transparencykey

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=3
DW_MINOR_VERSION=1