Changes in registration form to workaround client problems (EJAB-1262)

Changes included:
* Remove var in fixed field because Gajim and Tkabber display it to user
* Add workaround for Psi's overlap fields
* Add var=url attribute, required by Psi to display the field
* Provide the image URL as a copy-able form field

src/ejabberd_captcha.erl

@@ -126,15 +126,23 @@ create_captcha_x(SID, To, Lang, HeadEls, TailEls) ->
 		    [{"xmlns", ?NS_BOB}, {"cid", CID},
 		     {"max-age", "0"}, {"type", Type}],
 		    [{xmlcdata, B64Image}]},
-	    HelpTxt = io_lib:format(
-			translate:translate(
-			  Lang, "Visit ~s if you don't see the image"),
-			[get_url(Id ++ "/image")]),
+            HelpTxt = translate:translate(
+                                Lang,
+                                 "If you don't see the CAPTCHA image here, "
+                                 "visit the web page."),
+	    Imageurl = get_url(Id ++ "/image"),
 	    Captcha =
 		{xmlelement, "x", [{"xmlns", ?NS_XDATA}, {"type", "form"}],
 		 [?VFIELD("hidden", "FORM_TYPE", {xmlcdata, ?NS_CAPTCHA}) | HeadEls] ++
 		 [{xmlelement, "field", [{"type", "fixed"}],
 		   [{xmlelement, "value", [], [{xmlcdata, HelpTxt}]}]},
+		  {xmlelement, "field", [{"type", "hidden"}, {"var", "captchahidden"}],
+		   [{xmlelement, "value", [], [{xmlcdata, "workaround-for-psi"}]}]},
+		  {xmlelement, "field",
+		   [{"type", "text-single"},
+		    {"label", translate:translate(Lang, "CAPTCHA web page")},
+		    {"var", "url"}],
+		   [{xmlelement, "value", [], [{xmlcdata, Imageurl}]}]},
 		  ?VFIELD("hidden", "from", {xmlcdata, jlib:jid_to_string(To)}),
 		  ?VFIELD("hidden", "challenge", {xmlcdata, Id}),
 		  ?VFIELD("hidden", "sid", {xmlcdata, SID}),

src/mod_register.erl

@@ -217,7 +217,7 @@ process_iq(From, To,
 				 translate:translate(
 				   Lang,
 				   "Choose a username and password "
-				   "to register with this server")}]},
+				   "to register with this server.")}]},
 		    UField = {xmlelement, "field",
 			      [{"type", "text-single"},
 			       {"label", translate:translate(Lang, "User")},