Add adaptive SVG favicon and more SVG variants

See https://web.dev/building-an-adaptive-favicon/

Added more variant of the original Inkscape icon:

- Text SVG
- Vectorized text path SVG
- Optimized SVG icon

app/Template/layout.php

@@ -30,6 +30,7 @@
         <?= $this->hook->asset('css', 'template:layout:css') ?>
         <?= $this->hook->asset('js', 'template:layout:js') ?>
 
+        <link rel="icon" href="<?= $this->url->dir() ?>assets/img/adaptive-favicon.svg" type="image/svg+xml">
         <link rel="icon" type="image/png" href="<?= $this->url->dir() ?>assets/img/favicon.png">
         <link rel="apple-touch-icon" href="<?= $this->url->dir() ?>assets/img/touch-icon-iphone.png">
         <link rel="apple-touch-icon" sizes="72x72" href="<?= $this->url->dir() ?>assets/img/touch-icon-ipad.png">