When enabled, it adds "+n -m" after each file in the Files panel to show how
many lines were added and deleted, as with `git diff --numstat` on the command
line.
Previously, we had the following rules:
* file names were in red when unstaged or partially staged
* directory names were in red if unstaged, yellow if partially staged, and
green if fully staged
Red text on a black background can be hard to read, so instead I'm changing it
so that unstaged files have their names in the default text colour.
I'm also making it so that partially staged files are in yellow, just like how
partially staged directories are yellow (same deal with the commit files view
when adding to a custom patch).
So the new rules are:
* unstaged files/directories use the default colour
* partially staged files/directories are in yellow
* fully staged files/directories are in green
I've also done a refactor on the code clean up some dead code from when the file tree
outline was drawn with box characters, and I've made it so that the indentation in
each line is handled inside the function that draws the line rather than in the recursive
parent function. This makes it easier to experiment with things like showing the file
status characters on the left edge of the view (admittedly after experimenting with it,
I decided I didn't like it). Apologies for having a refactor and a functional change
in the one commit but by the time I was done, I couldn't be bothered going back and
retroactively splitting it into two halves.
