Version ao: saving your programs across restarts

This feature was very difficult. Lua Carousel launched without the ability to save to and load from files because I struggled to juggle two constraints:

• Reliability. I spent a long time trying to make autosave reliable on mobile devices. In particular, I didn't want to risk data loss because you switched apps and Carousel got shut down by the OS. To provide at least some value, I've given up on autosave for now and retreated to an easier interface: You'll have to explicitly hit the 'save' button to save.
• Narrow screens. As a cross-platform app, Lua Carousel is designed for a wide variety of screen widths, from phones in portrait mode to full-screen on a 27" external monitor. I wanted to always show a pane's filename, but without taking away precious space from the menu on a narrow screen. In the end I switched to a smaller font size for the title. Until now, Lua Carousel was built all out of a single font, mostly because I don't know what I'm doing when it comes to typography and accessibility.

As you can see, there were some compromises. I look forward to hearing after some experience what works well and what can be improved.

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This might be the final major feature in Lua Carousel, unless I come up with better ideas for a few open problems, particularly:

• Autosave, as I mentioned above.
• Ways to improve accessibility for all.
  • The editor currently uses 3 colors that aren't currently configurable. I'd love to find a way to customize them without making the settings page confusing.
  • ...

I'll be continuing to support Lua Carousel indefinitely, though, responding to feedback, fixing bugs and any future compatibility issues. And using it myself of course. I'd love to see what y'all build with it. And remember, it's open source, and it's ok to fork it. I won't be mad. In fact, I'll link to other forks in the repo, and happily point people to other forks when they seem relevant.