Implement responder chain in editor

[AngeloStavrow]

Closes #104 for the iOS app; must also be implemented for the Mac app, but that's a fair bit more work, so we'll punt on this for now.

This PR also adds some little quality-of-life fixes, like the Return key switching focus from the title field to the body field (but not vice versa), and a multi-line, auto-expanding title field.

[thebaer]

Very nice 👍 The Title field focus on load works perfectly!

One change I think we should implement, now that the title field auto-expands: add lineSpacing to that text field.

Otherwise, in my testing, I noticed that pressing Return to move from Title to Body only works once. If that's a quick fix, I think we should fix it here. Otherwise it's not critical, so we can fix it another time.

[AngeloStavrow]

Very nice 👍 The Title field focus on load works perfectly!

🎉

One change I think we should implement, now that the title field auto-expands: add lineSpacing to that text field.

Should be pretty straightforward. 👍

Otherwise, in my testing, I noticed that pressing Return to move from Title to Body only works once. If that's a quick fix, I think we should fix it here. Otherwise it's not critical, so we can fix it another time.

Good catch, I managed to repro this. I think I understand what's happening here, so I'll spend a little time this afternoon working on this; if possible, I'd like to push out another TestFlight release today/tomorrow to see how it's all working, and continue on #76 in the meanwhile for the App Store release of 1.0.1 while that's in public beta.

[thebaer]

Awesome. Works great!