Make blocks easier to use

This improves the user-facing API to include menu options for button names.

It also reports direction/force instead of x/y, which I believe makes the extension easier to work with.

- `〈button [start ▾] pressed?〉`
- `([direction ▾] of [left ▾] stick)`
For me, the reported direction is in Scratch's co-ordinate system. Are you sure the Gamepad API reads the correct values from your controller?