Makes save_timestamp conditional

- Add a .htconfig check to save_timestamp to prevent systematic
profiling
- Removes unused `mark_timestamp()` function including deleted code
comment

boot.php

@@ -1100,6 +1100,9 @@ class App {
 	}
 
 	function save_timestamp($stamp, $value) {
+		if (!isset($a->config['system']['profiler']) || !$a->config['system']['profiler'])
+			return;
+
 		$duration = (float)(microtime(true)-$stamp);
 
 		if (!isset($this->performance[$value])) {
@@ -1176,11 +1179,6 @@ class App {
 		return implode(", ", $callstack);
 	}
 
-	function mark_timestamp($mark) {
-		//$this->performance["markstart"] -= microtime(true) - $this->performance["marktime"];
-		$this->performance["markstart"] = microtime(true) - $this->performance["markstart"] - $this->performance["marktime"];
-	}
-
 	function get_useragent() {
 		return(FRIENDICA_PLATFORM." '".FRIENDICA_CODENAME."' ".FRIENDICA_VERSION."-".DB_UPDATE_VERSION."; ".$this->get_baseurl());
 	}

object/Conversation.php

@@ -145,7 +145,6 @@ class Conversation extends BaseObject {
 			$result[] = $item_data;
 		}
 
-		//$a->mark_timestamp();
 		return $result;
 	}