Formspec pixel perfection and atlases improvement proposals

[lua-rocks]

Problem

In the current implementation of the formspec, there is no universal way to strictly (pixel by pixel) control the position and size of GUI elements. The developer has no way to change the interface scaling method, preventing rounding to non-integer values, which causes each pixel on the screen to stretch or compress to random actual sizes.

Solutions

In fact, the engine is already capable of scaling formspec correctly. If you specify its dimensions not in abstract inventory slots but in real pixels, the scaling will be very precise, but it will create a bunch of problems. I think it would be nice to add such a command in the formspec syntax that switches it to 'pixel perfect mode,' in which all coordinates are specified in pixels rather than inventory slots.

In addition, I'd like to add one more thing that I would really like to see in formspecs - texture atlases, which I'm so used to in other engines. It would be really cool if the entire texture pack could be placed in one image, and the engine could create 'batches' from such atlases to improve performance.

I understand that this is a challenging task, but if you ever decide to completely rewrite the formspecs, please consider my request. Thank you! :)

Additional context

Related issues: #13777, #12524, #6527