Add option to format list of styles in select dropdown

I currently work on a site that requires a high number of different accessibility options. For aesthetic reasons, the list of links wasn't a great option for me, so I built an option to let administrators choose to display the list as a dropdown menu instead.

There is probably a better way to do the bit where I formed the select element for the block in the styleswitcher_block_view() function, but I'm pretty unfamiliar with Drupal's array rendering capabilities and just wanted to get it to work for now.

As far as I can tell, the dropdown and the list both work without any issues in my patched version.