Indent json when saving

[nixfloyd]

First of all: very nice tool! I use it to track and manage my personal todo list.

Main use case: I'm storing my .todos.json in a git repo, indenting allows one to have human-readable cand comprehensible diffs and history.

[sottey]

I have implemented this in ultodo, a fork of ultralist (which is amazing!) https://github.com/sottey/ultodo