🎨 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.

package-lock.json

@@ -4410,6 +4410,11 @@
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@@ -9992,6 +10002,15 @@
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+    "vuex-persist": {
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+        "lodash.merge": "^4.6.1"
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