Fix in-article links

These got broken since they were linking to just the article file as if it were still in the same folder. Apparently we did test the image links, but not the article links.

CuraSettingsGuide.py

@@ -315,7 +315,7 @@ def isArticleFile(self, filename: str) -> bool:
 		:return: True if the file name is the file name of an existing article,
 		or False if it isn't.
 		"""
-		return os.path.exists(os.path.join(os.path.dirname(__file__), "resources", "articles", filename))
+		return os.path.exists(filename)
 
 	@pyqtProperty(QObject, constant=True)
 	def containerStack(self) -> Optional[ContainerStack]:

QtMarkdownRenderer.py

@@ -43,6 +43,10 @@ def link(self, link, title, text):
 		"""
 		link = mistune.escape_link(link)
 		link_colour = UM.Qt.Bindings.Theme.Theme.getInstance().getColor("text_link").name()
+
+		if "://" not in link and link.endswith(".md"):  # Link to a different article.
+			link = os.path.join(self._images_path, link)
+
 		if not title:
 			return "<a href=\"{link}\"><font color=\"{colour}\">{text}</font></a>".format(colour=link_colour, link=link, text=text)
 		title = mistune.escape(title, quote=True)

resources/qml/ArticleText.qml

@@ -16,7 +16,8 @@ Text {
 
 	onLinkActivated: {
 		if(manager.isArticleFile(link)) {
-			var article_id = link.replace(/\.[^/.]*$/, "")
+			var article_id = link.replace(/\.[^/.]*$/, "");
+			article_id = article_id.replace(/.*\//, "");
 			manager.setSelectedArticleId(article_id);
 		} else {
 			Qt.openUrlExternally(link);