commands: fix update's help to be more accurate Branches can have multiple heads, so it doesn't make sense to speak of "the head of the current branch". What update really does is try to update to the *tip* of the current branch.

i18n: use encoding.colwidth() for correct column width Some encoding and language combinations (e.g.: UTF-8 and Japanese) cause encoding characters into sequence of bytes more than column width of them. So, encoding.colwidth() should be applied instread of len() on i18n strings. In addition to it, formatting by '%*s'/'%-*s' also uses "number of bytes" to calculate space padding size, and should be fixed, too.