New function to help resolve not-found files/directories (#217)

* ServerUIPropertiesMenu for Configurator to edit builtin UIProperties of MP

* fixed unregister-functions of CallbackManager

* Reducing menuItemHeight in Configurator to avoid overlapping of the menu items

* Fully rebuild the admins menu after a player rights changed

* Added function to FileUtil to improve realpath, so symbolic links can be resolved

* Fixed indentation

* Update FileUtil.php

Fixed error in case of an absolute path on Unix-like systems.

core/Files/FileUtil.php

@@ -236,4 +236,31 @@ abstract class FileUtil {
 	public static function isHiddenFile($fileName) {
 		return (substr($fileName, 0, 1) === '.');
 	}
+
+	/**
+	 * Shortens a path.
+	 * Opposed to realpath, it follows symbolic links.
+	 *
+	 * @param string $path
+	 * @return string
+	 */
+	public static function shortenPath(string $path) {
+		$root = substr($path, 0, 1) === '/';
+		$path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);
+		$parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
+		$absolutes = array();
+		foreach ($parts as $part) {
+			if ('.' === $part)
+				continue;
+
+			if ('..' === $part)
+				array_pop($absolutes);
+			else
+				array_push($absolutes, $part);
+		}
+		$path = implode(DIRECTORY_SEPARATOR, $absolutes);
+		if ($root)
+			$path = '/'.$path;
+		return $path;
+	}
 }