improved comments and made NowMs round properly

cmix/localTime.go

@@ -15,5 +15,5 @@ type localTime struct{}
 
 func (localTime) NowMs() int64 {
 	t := time.Now()
-	return (t.UnixNano() + int64(time.Millisecond)/2) / int64(time.Millisecond)
+	return (t.UnixNano() + int64(time.Millisecond)/2 + 1) / int64(time.Millisecond)
 }