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)`
This negation, at least in my testing, worked perfectly for the "turn to" block... but not for Scratch's trig. As it is, in order to move based on rotation but not rotate the sprite itself, trig is required... and this caused some very... odd bugs. Perhaps there is a better solution (or we can just patch Scratch, maybe)