clarify doc on dispatcher_email config setting.

An issue was brought up on the mailing list.

https://sourceforge.net/p/roundup/mailman/message/43383465/

The description of dispatcher_email sounds like it should be sent
email on issue creation. That's not it's role. Try to make it's role
more obvious.

Fix config.ini and reference.txt description.

Add the newissuecopy.py detector to send email on the creation of an
issue

Author: rouilj

doc/reference.txt

@@ -144,10 +144,10 @@ Section **main**
   below is used.
 
  dispatcher_email -- ``roundup-admin``
-  The 'dispatcher' is a role that can get notified of new items to the
-  database. It is used by the ERROR_MESSAGES_TO config setting. If the
-  email address doesn't contain an ``@`` part, the MAIL_DOMAIN defined
-  below is used.
+  The 'dispatcher' is a role that can get notified when errors occur
+  while sending email to a user. It is used by the ERROR_MESSAGES_TO config
+  setting. If the email address doesn't contain an ``@`` part, the
+  MAIL_DOMAIN defined below is used.
 
  email_from_tag -- default *blank*
   Additional text to include in the "name" part of the From: address used

roundup/configuration.py

@@ -1026,7 +1026,7 @@ def str2value(self, value):
             "mail -> domain is added."),
         (MailAddressOption, "dispatcher_email", "roundup-admin",
             "The 'dispatcher' is a role that can get notified\n"
-            "of new items to the database.\n"
+            "when errors occur while sending email to a user.\n"
             "It is used by the ERROR_MESSAGES_TO config setting.\n"
             "If no domain is specified then the config item\n"
             "mail -> domain is added."),