Use -/+ instead of </>

[cormacrelf]

It's not a purely cosmetic idea. + and - in the first column of text makes it very easy to get diff syntax highlighting when you copy and paste test output into GitHub comments. I find myself replacing the angle braces manually to get this effect.

Diff < left / right > :
 neutral
<[1, 2, 3, 4]
>[1–4]

Diff - left / right + :
 neutral
-[1, 2, 3, 4]
+[1–4]