Add option to specify diff program

[Sam Bull]

brz diff is not in colour. Please add an option to specify the diff program/command that brz uses, so this can be changed to e.g. colordiff.

[Jelmer Vernooij (jelmer)]

Isn't this what the --using option for 'brz diff' does?

[Sam Bull (dreamsorcerer)]

I meant a config option, to change the default program.

[Jelmer Vernooij (jelmer)]

The easiest way to do this is with an alias, add the following lines to ~/.config/breezy/breezy.conf:

[ALIASES]
diff = diff --using=/usr/bin/colordiff

[Sam Bull (dreamsorcerer)]

I think that solution is fine, but --using is not working correctly, see bug #1847915.