This allows us to separate accidentally unused, from explicitly unused
parameters, which allows us to turn on such checks in the compiler.

This adds the same touch gesture support for Windows as already added
for Unix. Note that it uses Windows gesture detection instead of our own
here though to give the user a familiar experience. Unfortunately that
means we lose the three finger tap.

This also raises the base requirements to Windows 7 as that's when
Windows got proper touch support.