Various unrelated minor updates to numerous classes/files (phpdoc, typo fixes, and related)

wire/core/Pagefile.php

@@ -1213,6 +1213,18 @@ class Pagefile extends WireData {
 		return isset($this->extras[$name]) ? $this->extras[$name] : null;
 	}
 
+	/**
+	 * Ensures that isset() and empty() work for dynamic class properties
+	 *
+	 * @param string $key
+	 * @return bool
+	 *
+	 */
+	public function __isset($key) {
+		if(parent::__isset($key)) return true;
+		return $this->get($key) !== null;
+	}
+
 	/**
 	 * Debug info
 	 * 

wire/core/TemplateFile.php

@@ -235,7 +235,7 @@ class TemplateFile extends WireData {
 	}
 	
 	/**
-	 * Render the template -- execute it and return it's output
+	 * Render the template -- execute it and return its output
 	 *
 	 * @return string The output of the Template File
 	 * @throws WireException if template file doesn't exist