Smspec c++

[joakim-hove]

Continuation of #526

equinor/libres#458
equinor/ert#167

Note: An important lesson learned while working with this task was the following:

In the old C code a quite common pattern was the following:

my_type * ptr = my_alloc( );

// Insert pointer in vector container, which will enable index based lookup. The 
// vector will alse take ownership of the object and discard it when going out of scope.
vector_insert_owned_ref( storage, ptr, my_free__);

// Insert pointer in hash table, to enable string based lookup. The hash table will not manage
// the underlying object.
hash_insert_ref(hash_table, "KEY", ptr);

This has worked reasonably well - when switching to C++ it was intially tempting to install value objects in a std::vector<my_class> instance, and then access pointers to those from a std::map<my_class *> - that does not work. The point is that when the std::vector<my_class> manages the instances they will not be in stable memory, and things fall apart. This pattern is quite common in librecl/libres!

[joakim-hove]

Note: this test is removed because the whole ecl_smspec_sort() functionality is removed.