rename variables

[kroggen]

These changes make the code more understandable

[kroggen]

I added an additional commit that decrease computation by pre-computing weight[index * weight_row_stride] and putting the result in weight

[kroggen]

There is both mat_vec_kernel and vec_mat_kernel functions

It would be better to have more meaningful names

[ankan-ban]

Thank you. Certainly more readable. I will merge this soon (if you can fix the conflicts).

[kroggen]

The conflicts were fixed