Add way to define deadzones / calibrate the analog sticks

[emoose]

Right now we just send the raw data along to XInput, would be nice if we can give the user a way to define their own deadzone though, since not many games allow to customize that.

I'm not sure if calibrating is important, ProconXInput has a method of calibrating ProCon sticks but it seems maybe that's only needed if the controller isn't sending the full 16-bit value that XInput uses (Xbox OG pads do, but Procon only sends an 8-bit value, which is maybe why that needs to be calibrated)

If anyone can think of a good way of implementing those please let me know!