characters to indicate removal immediately before change or addition

[gfixler]

I propose these signs for wherever removal precedes addition or change:

± ≂

The former could be yellow (green + red), the latter... cyan? These symbols could default to + and ~ for users who can't display the unicode versions, and maybe be allowed to show through a global var.

[airblade]

This would complicate the code because it would have to track what's happening on two lines at once, instead of just line by line. Also, as you point out, it's not obvious what colours they should have.

It's an interesting idea but on balance I don't feel it's worth it.

In terms of customisation, I just pushed some changes which (should!) make it easier to change the colours. The only thing you can't customise yet is the signs' symbols but I'll add that if there's demand – but not in a way which changes the meaning of the signs.

[gfixler]

I just realized you're already showing characters for both anyway. I didn't realize this, and I cede your points. Thanks.