Add options to have different indent width and line spacing.

[vincode-io]

  Great app. I’m very appreciative. I like the line height and indent size in iOS but would really like an option to make the indents about triple and the line heights half on MacOS. 

I’ve tried a lot of different font settings for the levels (great feature, BTW 👍 ) on MacOS but with no option to change the shallow indents and large line spacing, I still find it hard to know where I’m at, at a glance, compared to other outliners.

Originally posted by @Jason-Abbott in #191