C# SGMatrix and SGVectorList typemaps leak memory

In the out typemaps for both SGMatrix and std::vector<SGVector>, memory is allocated using malloc, but it's not freed.

shogun/src/interfaces/csharp/swig_typemaps.i

Lines 37 to 53 in c948611

	%typemap(out) shogun::SGVector<SGTYPE> {
	int32_t i;
	char *res;
	int len = $1.vlen;
	res = SG_MALLOC(char, sizeof(CTYPE) * len + sizeof(int32_t));
	((int32_t*)res)[0] = len;
	CTYPE * dst = (CTYPE *)(res + sizeof(int32_t));
	for (i = 0; i < len; i++) {
	dst[i ] = (CTYPE) $1.vector[i];
	}
	$result = (CTYPE *)res;
	}

shogun/src/interfaces/csharp/swig_typemaps.i

Lines 231 to 256 in c948611

	%fragment(SWIG_From_frag(std::vector<shogun::SGVector<SGTYPE>>), "header")
	{
	CTYPE* SWIG_From_dec(std::vector<shogun::SGVector<SGTYPE>>)
	(const std::vector<shogun::SGVector<SGTYPE>>& strings)
	{
	int32_t rows = strings.size();
	int32_t len = 0;
	for(auto& str : strings)
	len += str.vlen;
	char *res = SG_MALLOC(char, len * sizeof(CTYPE) + (rows + 1) * sizeof(int32_t));
	((int32_t *) res)[0] = rows;
	for(int32_t i = 0; i < rows; i++)
	((int32_t *) res)[i + 1] = strings[i].size();
	CTYPE *data = (CTYPE *)((int32_t *) res + rows + 1);
	for (auto& str : strings) {
	sg_memcpy(data, str.vector, str.vlen * sizeof(SGTYPE));
	data = data + str.size();
	}
	return (CTYPE *) res;
	}
	}

These allocated buffers are passed to C# code as IntPtr, and can't be deallocated from there.

[stale]

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I have a simple solution in mind. I will attend to this issue this weekend.

[gf712]

No rush! I just added this bot to clean up the repo