Implement "send_link" macro (#6767)

When to_chat gets converted to a proc, then the construct of to_chat(some, link(url)) will no longer work. Or will produce odd results.

As a result, the send_link macro is now created. Replaced existent instances of the previous construct and added a simple grep check for this as well. It won't catch all, probably, but it'll catch the most common instances.

code/modules/client/client procs.dm

@@ -194,9 +194,9 @@
 				else if (alert("This will open the Github page in your browser. Are you sure?",, "Yes", "No") == "Yes")
 					if (href_list["pr"])
 						var/pr_link = "[config.githuburl]pull/[href_list["pr"]]"
-						to_chat(src, link(pr_link))
+						send_link(src, pr_link)
 					else
-						to_chat(src, link(config.githuburl))
+						send_link(src, config.githuburl)
 
 			// Forum link from various panels.
 			if ("forums")
@@ -671,7 +671,7 @@
 			log_debug("Unrecognized process_webint_link() call used. Route sent: '[route]'.")
 			return
 
-	to_chat(src, link(linkURL))
+	send_link(src, linkURL)
 	return
 
 /client/verb/show_greeting()

code/modules/client/preferences.dm

@@ -251,7 +251,7 @@ datum/preferences
 
 	if(href_list["preference"] == "open_whitelist_forum")
 		if(config.forumurl)
-			to_chat(user, link(config.forumurl))
+			send_link(user, config.forumurl)
 		else
 			to_chat(user, "<span class='danger'>The forum URL is not set in the server configuration.</span>")
 			return