Ability to persist in browser local storage hidden columns

[Adesin-fr]

This project is really nice.
I can even see that my customers will like it !

But I can even see they will love the feature that allow to hide columns , and ask me if this setting can be persisted for each table.

I don't see it too much difficult to implement : storing the "shown" list in the local storage will be easy, we just need to set a "table id" to save each table's list on its own variable.

I can make this modification and make a PR when done.

What about this ?