Update to c++17

CMakeLists.txt

@@ -257,7 +257,7 @@ ENDIF()
 # Grouped compiler settings ########################################
 IF ((CMAKE_C_COMPILER_ID MATCHES "GNU") AND NOT MINGW)
   IF(NOT ASSIMP_HUNTER_ENABLED)
-    SET(CMAKE_CXX_STANDARD 11)
+    SET(CMAKE_CXX_STANDARD 17)
     SET(CMAKE_POSITION_INDEPENDENT_CODE ON)
   ENDIF()
   # hide all not-exported symbols