Serde impls for static size matrices larger than 127 (in either dimension)

I am interested in implementing this because that functionality would be rather useful to me. AFAIK this was not an issue when I used `MatrixArray` for storage but with `MatrixVec` the `Serialize` and `Deserialize` traits are not implemented if either of the `Dim` does not.

The biggest roadblock to actually implement it is that foreign traits (`Serialize`, `Deserialize`) cannot be implemented for foreign types (the typenum types). Without true const generics this will be a bit messy I guess (actually adding all dimensions to nalgebra, or more realistically using a newtype generic over the typenum values), so I'm not sure if this feature is even a true possibility right now? As far as I understand the only actually clean approach would be to add serde support to typenum directly (maybe behind a feature flag).