Convert cmd_modenotice into an optional module

docs/conf/modules.conf.example

@@ -1058,6 +1058,11 @@
 # would likely be immediately bounced by services.
 #<module name="m_mlock.so">
 
+#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
+# Modenotice module: Adds the /MODENOTICE command that allows opers to
+# send notices to all users having the given user mode(s) set.
+#<module name="m_modenotice.so">
+
 #-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
 # MsSQL module: Allows other SQL modules to access MS SQL Server 
 # through a unified API.

src/modules/m_modenotice.cpp

@@ -48,8 +48,24 @@ next_user:	;
 
 	RouteDescriptor GetRouting(User* user, const std::vector<std::string>& parameters)
 	{
-		return ROUTE_BROADCAST;
+		return ROUTE_OPT_BCAST;
 	}
 };
 
-COMMAND_INIT(CommandModeNotice)
+class ModuleModeNotice : public Module
+{
+	CommandModeNotice cmd;
+
+ public:
+	ModuleModeNotice()
+		: cmd(this)
+	{
+	}
+
+	Version GetVersion() CXX11_OVERRIDE
+	{
+		return Version("Provides the /MODENOTICE command", VF_VENDOR);
+	}
+};
+
+MODULE_INIT(ModuleModeNotice)

src/modules/m_spanningtree/compat.cpp

@@ -286,6 +286,13 @@ bool TreeSocket::PreProcessOldProtocolMessage(User*& who, std::string& cmd, std:
 
 		params.insert(params.begin()+2, ConvToStr(ServerInstance->Time()));
 	}
+	else if (cmd == "MODENOTICE")
+	{
+		// MODENOTICE is always supported by 2.0 but it's optional in 2.2.
+		params.insert(params.begin(), "*");
+		params.insert(params.begin()+1, cmd);
+		cmd = "ENCAP";
+	}
 
 	return true; // Passthru
 }