Consider renaming `Export Wallet…` and `Import Wallet…`

[casey]

I was looking for label import and export, and I originally couldn't find it because I didn't think to look in Import Wallet… and Export Wallet…, since those sounded like they were for importing / exporting the whole wallet, i.e., including private keys.

I was thinking that maybe they should be named Import… and Export… since they're general, and support a bunch of things other than importing/exporting the whole wallet.

[craigraw]

Yes, I agree the menu item name isn't a great fit when it comes to labels. But just using Import... and Export... might be net loss since at least all the functions are wallet related. People might start thinking this is the place "import" a transaction they want to broadcast, for example. I don't like it, but maybe Import Wallet or Labels...