Implemented a global option to suppress logs by ids

You can now use -suppress LOGID or -s LOGID to not print logs with the given
ids.  This is a global option which means it is applicable to all commands.
It can be specified more than once.

duplicacy/duplicacy_main.go

@@ -159,6 +159,10 @@ func setGlobalOptions(context *cli.Context) {
 		}()
 	}
 
+	for _, logID := range context.GlobalStringSlice("suppress") {
+		duplicacy.SuppressLog(logID)
+	}
+
 	duplicacy.RunInBackground = context.GlobalBool("background")
 }
 
@@ -2069,6 +2073,11 @@ func main() {
 			Name:  "comment",
 			Usage: "add a comment to identify the process",
 		},
+		cli.StringSliceFlag{
+			Name:  "suppress, s",
+			Usage: "suppress logs with the specified id",
+			Argument: "<id>",
+		},
 	}
 
 	app.HideVersion = true

src/duplicacy_log.go

@@ -45,6 +45,13 @@ func setTestingT(t *testing.T) {
 	testingT = t
 }
 
+// Contains the ids of logs that won't be displayed
+var suppressedLogs map[string]bool = map[string]bool{}
+
+func SuppressLog(id string) {
+	suppressedLogs[id] = true
+}
+
 func getLevelName(level int) string {
 	switch level {
 	case DEBUG:
@@ -145,6 +152,12 @@ func logf(level int, logID string, format string, v ...interface{}) {
 		defer logMutex.Unlock()
 
 		if level >= loggingLevel {
+			if level <= ERROR && len(suppressedLogs) > 0 {
+				if _, found := suppressedLogs[logID]; found {
+					return
+				}
+			}
+
 			if printLogHeader {
 				fmt.Printf("%s %s %s %s\n",
 					now.Format("2006-01-02 15:04:05.000"), getLevelName(level), logID, message)