using and exporting source and explanation

src/model/translation.py

@@ -10,6 +10,10 @@ class Translation:
     def __init__(self, translation_xml):
         translation = translation_xml.querySelector("translation")
         self.translation = translation.textContent if translation else ""
+        self.source = translation.getAttribute("source") or ""
+        
+        explanation = translation_xml.querySelector("explanation")
+        self.explanation = explanation.textContent if explanation else ""
         
         self.tags = {}
         for tag_xml in translation_xml.querySelectorAll("tagsContainer tag"):