Drawing multiple cells and rulers

Let's parse a csv file.

Tiny 58 bytes csv parser, now it's time to implement spreadsheet formulae.

Starting selection, gosh, I love doing gui apps in postfix programming languages.

Cells with computed values will have a different background.

Wrote a little spreadsheet evaluator in 4000 bytes of #uxn bytecode.

Started improving input, added a form at the bottom that let's me see the spreadsheet's formulae and edit them.

Aight, back to building a spreadsheet program in assembly. I will try to display border highlights around the region read in each of the formulae.
https://git.sr.ht/~rabbits/nebu/tree/main/item/src/nebu.tal

Implemented highlight for cells from which the formulae is pulling its values.

I'm finally building my dream spreadsheet application, and it's going to be a mere 5kb program that runs on all our old devices.

I seem to be having an issue pulling results from formulae cells.. 🤔

Fixed issue, added scrolling and display selection size. Up next, doing other functions than SUM, I'd like to have AVERAGE() and PRODUCT().

I've been thinking about using:
- `a5:c8` for an array reference
- `a5;` for a single cell reference

Starting to dive into the more fun parts of spreadsheets UX!

Implementing this is endlessly fascinating. I should have tried this much earlier on.