Attempt to fix CMake

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.9)
 project(tangle_project)
-set (CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 
 option(DISTRIBUTED "Use MPI" ON)
 option(MULTITHREADED "Use OpenMP" OFF)