Make Lua optional

[LoganDark]

Including Lua is wasted space when it's not used, please put it behind a Cargo feature (even if that's enabled by default). Honestly most of the crate should be behind cargo features.

[fenollp]

Hi @LoganDark thanks for raising this.
We appreciate your comment and welcome discussion. cc at #55

Can you tell us a bit more about how you're using libremarkable?

What other parts of the crate do you feel should be behind features?

[LoganDark]

Can you tell us a bit more about how you're using libremarkable?

I'm going to use libremarkable in 2 programs that are designed to work together:

• An application that the user runs to input calibration data. This will require the GUI stuff, but not Lua
• A shared object that intercepts xochitl's pen events, ReCept-style. This does NOT require the GUI stuff, only the input device scanning (so I know which /dev/input/eventX is the wacom digitizer)

In the former case I need the entire application system, input event handling and all. But in the latter case I only need a small subset of libremarkable.

[bkirwi]

Yeah, I think this use case is addressed by #55. (Which we don't have an issue for yet, so might as well keep this one open.)

It's worth mentioning that appctx is not very heavily used, compared to the rest of the library. Many libremarkable users end up using the low-level device support and handrolling a toolkit suited to the needs of their app. If you're not happy with how appctx works, that's a good way to keep yourself unblocked! (Though we should follow through on #55 regardless to keep builds lighter.)

[bkirwi]

#55 is merged, so I'll mark this done. We should have a proper release out soon within the next week or two I imagine...