Set white-space property to nowrap on editor lines

Allows inline-block elements adding to the line to no
be wrapped when the window is resized.

Closes #211

static/editor.css

@@ -104,3 +104,7 @@
   pointer-events: none;
   z-index: -1;
 }
+
+.editor .line {
+  white-space: nowrap;
+}