Bugfix: Invalid memory deletion.

Bugfix: Invalid memory deletion.

The memory is being incorrectly deleted for multiple reasons.
1) The type is not f_string_t, it is struct dirent.
2) The index within a listing is already a pointer.
3) The listing itself is already a pointer.
4) Remove extra delete commands.
5) The memory is not being deleted on certain errors.

These problems have been exposed by the unit tests.

Also replace macro_f_memory_structure_increment() with f_string_dynamics_increase().