Added aspect ratio option for dials

[apisarenco]

I have custom "icons" for the dials, that I've made, and they all use a different aspect ratio, so I needed it to work for me.

The changes include:

• New fields in the options page, with new CSS to accommodate the change (using 2 inputs in a single table cell, together with text)
• New validation rules for the inputs
• Updated HTML and CSS of the New Tab, to apply the aspect ratio on thumbnails, folders and + sign.

I had to change the way that the title is inserted, since the 4:3 ratio was used for the whole dial, and now it is used only for the thumbnail itself.

What I didn't do: I didn't update the thumbnail service URL. It's a string, which includes ratio. I guess it should have the thumbnail size inserted automatically when you choose the service from a list. Maybe another time.