The uemis code is wild. It simply doesn't deallocate memory
and uses global variables. To get this under control, create
a "struct uemis" and make the functions exported by "uemis.h"
members of "struct uemis". Thus, we don't have to carry around
a parameter for the state of the importing process.
Turn a linked list of "helper" structures (one per imported dive)
into a std::unordered_map, to fix leaking of the helper structures.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
