fixed incorrect msgmax calculation in response to WHO reply code 352, which didn't account for the":nick!user@" part before hostname nor the space before $priv. additionally, an upcoming RSS feature would sometimes need to send news before reading any messages back from server (and WHO reply code 352 might never return or might not return on time), so a conservative fallback msgmax heurestic calculation was added before the evasdrop loop. it uses a maximum hostname length of 63 from RFC 2812 and accounts for the the non-ident tilde (~) that might get prepended to username until we know what the actual hostname and username are.