fix: plug memory leaks in haploid_highd destructor

The free_mem() function was not releasing several allocated arrays,
causing significant memory leaks during evolution simulations with
CROSSOVERS recombination model.

Fixed by adding deletion of:
- genome array (auxiliary array for crossover points)
- crossovers array (crossover points storage)
- trait_stat array (trait statistics)
- trait_covariance matrix (2D array)
- trait_weights array
- gsl_rng generator (via gsl_rng_free)

This reduces memory growth during evolution, though further
investigation is needed for remaining accumulation during evolve().

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: corneliusroemer

src/haploid_highd.cpp

@@ -187,9 +187,18 @@ int haploid_highd::free_mem() {
 		cerr <<"haploid_highd::free_mem(): No memory allocated!\n";
 		return HP_BADARG;
 	} else {
+		delete [] genome;
+		delete [] crossovers;
 		delete [] allele_frequencies;
 		delete [] gamete_allele_frequencies;
 		delete [] trait;
+		delete [] trait_stat;
+		for (int t = 0; t < number_of_traits; t++){
+			delete [] trait_covariance[t];
+		}
+		delete [] trait_covariance;
+		delete [] trait_weights;
+		gsl_rng_free(evo_generator);
 		mem = false;
 		return 0;
 	}