[for @Raytracing] No Operators 3D

Description

This is to help @Raytracing with the project below. See the (slightly long) discussion thread there... (I'll probably unshare this once changes are included there.) I think the idea behind this is to show how it's possible to create a "3D engine" in Scratch without using any 'math'. I'm looking forward to seeing how @Raytracing adds perspective without any operator blocks... :D I can see how some of this could be helpful in avoiding trig, but TBH I think it takes it a bit far, unless it's meant to be taken as some kind of 'challenge' – I mean doing a simple subtraction by moving the sprite seems more complicated than just using a minus block, and checking if a value is -ve/+ve by moving the sprite and testing if it's then touching the edge or another sprite... :/