Currently, the only colors available to --pretty=format
users are red, green, and blue. Rather than expand it with a
few new colors, this patch makes the usual config color
syntax available, including more colors, backgrounds, and
attributes.
Because colors are no longer bounded to a single word (e.g.,
%Cred), this uses a more advanced syntax that features a
beginning and end delimiter (but the old syntax still
works). So you can now do: