Merge branch 'master' into cxx17

diff --cc src/EC/Manager.hpp
index b5ffe13b2f4b365aaaadf81d59fde4398c880692,4c1c8e1af9dedfecf78408700bd060cf83acf668..17f35a06390b5b4f32a30a1ebdad67faa8ce04ac
--- 1/src/EC/Manager.hpp
--- 2/src/EC/Manager.hpp
+++ b/src/EC/Manager.hpp
@@@ -187,9 -199,11 +198,11 @@@ namespace E
          Manager()
          {
              resize(EC_INIT_ENTITIES_SIZE);
 -            if(ThreadCount >= 2) {
 +            if constexpr(ThreadCount >= 2) {
                  threadPool = std::make_unique<ThreadPool<ThreadCount> >();
              }
+ 
+             deferringDeletions.store(0);
          }
  
      private: