qtconsole: wrap argument list in tooltip to match width of text body previously, a function with a long argument list would produce a very wide tooltip, hurting readability. Since the width of the docstring body is chosen by the developer whereas the formatting of the argument list is currently not, it's reasonable to wrap the argument list width to the maximum of a) 80 characters, or b) maximum length of a line in the docstring body. This improved readability, without unduly affecting the appearence of the docstring body itself. closes #2661