Enforce c++14 in codebase
This MR enforces C++14 and also make a small fix in a assignment in format.h which wrongly errors in some supported old versions of GCC.
This is needed for vtk-m to complete this MR
This MR enforces C++14 and also make a small fix in a assignment in format.h which wrongly errors in some supported old versions of GCC.
This is needed for vtk-m to complete this MR