A std::map is in an invalid state when just zero-initialized, and needs
to be initialized by its constructor. As this initilization may be done
after the first call to Register, a crash will typically happen.
To fix this wrap all accesses to the map with a Meyers Singleton. Also
remove the extra Array - most accesses are using the key, and the few
format list iterations all sort the result afterwards anyway.
Fixes#201.
* This extended format has been added in addition to the normal STL export format of Netgen
* The extended format can also be read by Netgen without any changes to the STL reader code
* ToDo: The code needs to be optimised and sped up.... current implementation is not sufficiently elegant!
