make `ergo genpasswd` warn for bad passwords

ergo.go

 		} else {
 			password = getPassword()
 		}
+		if err := irc.ValidatePassphrase(password); err != nil {
+			log.Printf("WARNING: this password contains characters that may cause problems with your IRC client software.\n")
+			log.Printf("We strongly recommend choosing a different password.\n")
+		}
 		hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.MinCost)
 		if err != nil {
 			log.Fatal("encoding error:", err.Error())

irc/accounts.go

 	}
 }
 
-// validatePassphrase checks whether a passphrase is allowed by our rules
-func validatePassphrase(passphrase string) error {
+// ValidatePassphrase checks whether a passphrase is allowed by our rules
+func ValidatePassphrase(passphrase string) error {
 	// sanity check the length
 	if len(passphrase) == 0 || len(passphrase) > 300 {
 		return errAccountBadPassphrase
 }
 
 func (am *AccountManager) NsResetpass(client *Client, accountName, code, password string) (err error) {
-	if validatePassphrase(password) != nil {
+	if ValidatePassphrase(password) != nil {
 		return errAccountBadPassphrase
 	}
 	account, err := am.LoadAccount(accountName)
 		return nil
 	}
 
-	if validatePassphrase(passphrase) != nil {
+	if ValidatePassphrase(passphrase) != nil {
 		return errAccountBadPassphrase
 	}