Implemented client_count condition

Config option client_count_less_than (uint) determines if notifications
will be sent based on how many IRC clients are connected to ZNC.  A
value of zero disables this condition (always met), otherwise only sends
notifications if the number of connected clients is less than the
configured threshold.

Personal use case is client_count_less_than = 2, in that I always have
Irssi connected from my server, but if also connected from my phone, I
don't want duplicate notifications.

notifo.cpp

@@ -71,6 +71,9 @@ class CNotifoMod : public CModule
 			// Notifo user account and secret
 			options["username"] = "";
 			options["secret"] = "";
+
+			// Notification conditions
+			options["client_count_less_than"] = "0";
 		}
 		virtual ~CNotifoMod() {}
 
@@ -139,6 +142,27 @@ class CNotifoMod : public CModule
 #endif
 		}
 
+		/**
+		 * Check how many clients are connected to ZNC.
+		 *
+		 * @return Number of connected clients
+		 */
+		unsigned int client_count()
+		{
+			return user->GetClients().size();
+		}
+
+		/**
+		 * Check if the client_count condition is met.
+		 *
+		 * @return True if client_count is less than client_count_less_than or if client_count_less_than is zero
+		 */
+		bool client_count_less_than()
+		{
+			unsigned int value = options["client_count_less_than"].ToUInt();
+			return value == 0 || client_count() < value;
+		}
+
 		/**
 		 * Determine if the given message matches any highlight rules.
 		 *
@@ -167,7 +191,17 @@ class CNotifoMod : public CModule
 		 */
 		bool notify_channel(const CNick& nick, const CChan& channel, const CString& message)
 		{
-			return highlight(message);
+			if (!highlight(message))
+			{
+				return false;
+			}
+
+			if (!client_count_less_than())
+			{
+				return false;
+			}
+
+			return true;
 		}
 
 		/**