Properly support extended scan codes on Windows
Properly support extended scan codes on Windows

Recently we switched to scan codes from the virtual key codes that were
keyboard layout specific. However it seems like originally Windows only
supported 8-bit scan codes and later extended those. Those scan codes
have the following shape: `E0xy`. However the low level keyboard hook
API by default only returns the old 8-bit `xy` scan codes. There however
is a `flags` field you can look at to determine if it was meant to be an
extended scan code.

CryZe/livesplit-core,CryZe/livesplit-core