Added data classes bases, Trivial modifications to many files

Update .gitignore, .htaccess, and 19 more files...

commons/content/data/metadata.php

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+<?php
+// Making sure the file is included and not accessed directly.
+if(basename(__FILE__) == basename($_SERVER["SCRIPT_FILENAME"])) {
+	header('HTTP/1.1 403 Forbidden');
+	die();
+}
+
+// Including required helpers.
+include_once 'commons/langs.php';
+
+// Including subclasses.
+include_once 'commons/content/data/opengraph.php';
+include_once 'commons/content/data/twitter_card.php';
+
+class ContentMetadata {
+
+}
+
+?>

commons/content/data/opengraph.php

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+<?php
+// Making sure the file is included and not accessed directly.
+if(basename(__FILE__) == basename($_SERVER["SCRIPT_FILENAME"])) {
+	header('HTTP/1.1 403 Forbidden');
+	die();
+}
+
+// Including required helpers.
+include_once 'commons/langs.php';
+
+class OpenGraphData {
+	public string $title;
+	public string $description;
+	public string $type;
+	public string $url;
+	public string $image;
+	public string $image_type;
+	
+	function __construct(array $title, array $description, string $type, string $url, string $image,
+	                     string $image_type) {
+		global $default_language;
+		global $user_language;
+		
+		$this->title = array_key_exists($user_language, $title) ? $title[$user_language] :
+			(array_key_exists($default_language, $title) ? $title[$default_language] : $title[0]);
+		$this->description = array_key_exists($user_language, $description) ? $description[$user_language] :
+			(array_key_exists($default_language, $description) ? $description[$default_language] : $description[0]);
+		
+		$this->type = $type;
+		$this->url = $url;
+		$this->image = $image;
+		$this->image_type = $image_type;
+	}
+	
+	static function from_json(array $json_data): ?OpenGraphData {
+		foreach(["title", "description", "type", "url", "image", "image_type"] as $wantedKey) {
+			if(!key_exists($wantedKey, $json_data)) {
+				return null;
+			}
+		}
+		
+		return new OpenGraphData(
+			$json_data["title"],
+			$json_data["description"],
+			$json_data["type"],
+			$json_data["url"],
+			$json_data["image"],
+			$json_data["image_type"]
+		);
+	}
+}
+?>

commons/content/data/twitter_card.php

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+<?php
+
+/*enum Suit {
+case Hearts;
+case Diamonds;
+case Clubs;
+case Spades;
+}*/
+
+// See: https://developer.twitter.com/en/docs/twitter-for-websites/cards/overview/markup
+/*class ContentTwitterMetadata {
+public string $title;
+public string $description;
+public string $type;
+public string $url;
+public string $image;
+public string $image_type;
+}*/
+
+?>