Refactorings & Matrix * Sparse-Matrix support

[alyst]

This PR

• simplifies a bit the wrapper generation logic
• some unnecessary "type piracy" was removed (A*B calls mul!(C,A,B) already)
• streamlines testing, so that all 4 numeric types are covered
• @test_blas macro replaced by conventional @test macro in combination with @blas macro that allows more fine-grained checks of whether Sparse BLAS MKL methods are being called
• last but not the least: the support for Matrix * SparseMatrixCSC multiplication via Sparse BLAS (currently it's being handled by the Base Julia). It uses the fact that ColMajorRes = ColMajorMtx*SparseMatrixCSC is the same as RowMajorRes = SparseMatrixCSR*RowMajorMtx. Unfortunately, the older Sparse BLAS API doesn't support the combination of one-based Sparse matrices and row-major storage, so I had to add some boilerplate code to leverage newer mkl_sparse_xxx API.