Take `CsMatViewI` as input for smmp

[vbarrielle]

When I implemented smmp, I followed quite closely the reference paper, but in doing so I made an API taking slices as input. In consequence the implementation is not allowed to rely on the guarantees of CsMatBase, for instance the fact that the indices are in range. This prevents some optimization opportunities.

I suggest using the 0.10 version to change this API, and take CsMatViewI as input, to be able to perform these optimizations later on if necessary.