🎨 Add theme support

- Move root (var) style properties to `/assets/css/themes.scss`
- Improve mobile navigation
- Create section component for the collapsable sections.
- Create logo component, so color can be changed.

- Add settings page
- Add option to select theme color
- Add option to select theme background
- Add option to enable/disable multi-colored frames.

- Add settings to VueX Store
- Persist VueX store in LocalStorage.

nuxt.config.js

@@ -86,10 +86,12 @@ export default {
   ** Customize the progress-bar color
   */
   loading: { color: '#88FB4F' },
+
   /*
   ** Global CSS
   */
   css: [
+    '@/assets/css/themes.scss',
     '@/assets/css/fonts.scss',
     '@/assets/css/styles.scss'
   ],
@@ -97,6 +99,7 @@ export default {
   ** Plugins to load before mounting the App
   */
   plugins: [
+    { src: '~/plugins/vuex-persist' }
   ],
   /*
   ** Nuxt.js dev-modules