feat: don't flush ostream after every logline; +26% speed

Log.cpp

@@ -32,7 +32,7 @@ public:
 
 		std::ostream* os = getOs(lvl);
 		if (os) {
-			*os << sbuf << std::endl;
+			*os << sbuf << '\n';
 		}
 	};
 
@@ -83,7 +83,7 @@ private:
 			else
 				*os << sbuf;
 
-			*os << std::endl;
+			*os << '\n';
 		}
 	}