histedit: add a config allowing changing histedit rule line length limit Since many users are using terminals wider than 80 chars there should be an option to have longer lines in histedit editor. Even if the summary line is shorter than 80 chars after adding action line prefixes (like "pick 7c2fd3b9020c") it doesn't fit there anymore. Setting it to for example 110 would be a nice option to have.