Add matfaust mex wrappers bsr_mat_to_sp_mat functions.

There were missing in c460d7e6.

wrapper/matlab/src/faust_factors.hpp

 #include "faust2Mx.h"
 #include "class_handle.hpp"
 #include "faust_TransformHelper.h"
+
+/**
+ * These functions allow to convert a MatBSR factor of a Faust::TransformHelper to MatSparse, as the bsr matrices are not supported in Matlab.
+ */
+template <typename SCALAR>
+mxArray* bsr_mat_to_sp_mat(int id, Faust::TransformHelper<SCALAR,Cpu>* core_ptr);
+template <typename SCALAR>
+mxArray* bsr_mat_to_sp_mat(int id, Faust::TransformHelper<SCALAR,GPU2>* core_ptr);
+
+
 template <typename SCALAR, FDevice DEV>
 void faust_factors(const mxArray **prhs, const int nrhs, mxArray **plhs, const int nlhs)
 {
@@ -15,9 +25,31 @@ void faust_factors(const mxArray **prhs, const int nrhs, mxArray **plhs, const i
 		plhs[0] = transformFact2SparseMxArray(id,core_ptr);
 //
 //		plhs[0] = FaustSpMat2mxArray(*dynamic_cast<const Faust::MatSparse<SCALAR,Cpu>*>(core_ptr->get_gen_fact(id)));
-	else
+	else if(core_ptr->is_fact_dense(id))
 		plhs[0] = transformFact2FullMxArray(id,core_ptr);
 //		plhs[0] = FaustMat2mxArray(*dynamic_cast<const Faust::MatDense<SCALAR,Cpu>*>(core_ptr->get_gen_fact(id)));
+	else if(core_ptr->is_fact_bsr(id))
+	{
+		plhs[0] = bsr_mat_to_sp_mat(id, core_ptr);
+	}
+	else
+		mexErrMsgTxt("Unhandled type of matrix");
+
+}
 
+template <typename SCALAR>
+mxArray* bsr_mat_to_sp_mat(int id, Faust::TransformHelper<SCALAR,Cpu>* core_ptr)
+{
+	auto bsr_mat = dynamic_cast<const MatBSR<SCALAR, Cpu>*>(core_ptr->get_gen_fact(id));
+	auto sp_mat = bsr_mat->to_sparse();
+	return FaustSpMat2mxArray(sp_mat);
 }
 
+#ifdef USE_GPU_MOD
+template <typename SCALAR>
+mxArray* bsr_mat_to_sp_mat(int id, Faust::TransformHelper<SCALAR, GPU2>* core_ptr)
+{
+	//TODO: nothing to do now because MatBSR aren't supported on GPU2, implement it later
+	return nullptr;
+}
+#endif