Don't leave hanging katexserver.

formatitko.py

@@ -48,11 +48,11 @@ doc = doc.walk(transform, context)
 # setting out to TeX
 doc.content = [Group(*doc.content, metadata={"language":language})]
 
-# Initialize KaTeX client (this runs the node app and connects to a unix socket)
-katexClient = KatexClient()
 # Initialize the image processor (this just keeps some basic state)
 imageProcessor = ImageProcessor(args.img_public_dir, args.img_web_path, *args.img_lookup_dirs)
 
+# Initialize KaTeX client (this runs the node app and connects to a unix socket)
+with KatexClient() as katexClient:
 	# Generate HTML and TeX out of the transformed document
 	open(args.output_html, "w").write(html(doc, katexClient, imageProcessor))
 	open(args.output_tex, "w").write(tex(doc, imageProcessor))

katex.py

@@ -56,3 +56,9 @@ class KatexClient:
 
 	def endgroup(self):
 		self._client.sendall("endgroup\n".encode("utf-8"))
+
+	def __enter__(self):
+		return self
+
+	def __exit__(self, type, value, tb):
+		self._server_process.terminate()