weboob.tools.application: let bcall_errors_handler return exit code
Currently, weboob commands still return 0 even when an exception is raised. Let bcall_errors_handler decide the return code instead of always 0. A good return code is hard because of several things: * there might be multiple exceptions in a BCallErrors, so values returned by bcall_error_handler (single exception) cannot easily be combined * the base implemententation of bcall_errors_handler cannot be polluted with a lot of exception subclasses So, any non-MoreResultsAvailable will cause a non-zero return code. Should fix https://git.weboob.org/weboob/devel/issues/74.