Replace memory allocation type to pointer based to avoid deep-call copying

[fxllenfx]

yes

[PolskaKrowa]

Try looking at the contributing.md file before making a pull request.

Also, the pointer association that you used does not actually fix a "huge memory leak" but only reduces memory requirements by a few kilobytes.
Actually fixing a memory leak would require meticulous temporary object freeing and thorough testing with valgrind. Were those conditions met?

I'll also like to ask about your BWR interface files. The whole premise of this project is to allow people to make nuclear physics simulations, not just BWR simulations. Making a C interface would probably include modifying the existing interface to implement all of the provided functions from the internal library into C callable functions.