add Matrix tests for multiplication by permutations

[rfourquet]

No description provided.

[wbhart]

Seems to cause test failures. Could you possibly look into why. Ignore all the failed builds with an exclamation mark, just look at the ones with an X.

[rfourquet]

Seems to cause test failures

Ah yes thanks for checking, this was due to a last second change beforfe pushing.

[rfourquet]

More errors, some of them will be automatically fixed if #504 is merged. And maybe the other errors would be fixed by #496.

[wbhart]

The Julia 1.2 errors seem to be real, so I don't think we should merge this yet until we understand why they are happening. Are they using == instead of isapprox?

[rfourquet]

Yeah some errors look definitely real. I didn't investigate too closely, but something seems to have changed in some Julia versions in how reduce(vcat, ...) is handled. That's why I think #496 would solve the problem. If not, or if that PR doesn't get merged, I will look into changing the tests to make them pass.

[rfourquet]

That's why I think #496 would solve the problem

Actually I think it will not, I will fix the problem here.