[feature] make theme images clickable

[apoleon33]

See #43

Note:

Changed en.json and fr.json from:

"omega_light": "Omega Light",

to:

          "omega_dracula": {
            "name": "Omega Dracula",
            "url": "https://github.com/Ratakor/Omega-Dracula-Theme"
          },

Still need to see if that breaks anything on the rest of the website though.