Windows version of VirtualBox should declare itself DPI-aware

[Sophie]

I use a custom DPI setting on Windows and as far as I can tell, VirtualBox is fine with high DPI settings. However, it doesn't ​declare itself DPI-aware, meaning that on Windows 7 by default it will be subject to DPI Virtualization, where the OS gives the app an off-screen 96 DPI surface to draw on, which the OS then scales up for display. Needless to say, this results in blurry interfaces. I think it's probably a good idea if VirtualBox were to declare itself DPI-aware.

Normally I'd get around this by setting the compatibility properties, but my version of VirtualBox is a 64-bit app and as such, Windows 7 doesn't allow me to change those.