better issue template
-If you're having problems converting from or to a mesh format, remember to attach a mesh that shows the problem. This will enable other people to reproduce and fix the problem.
+* Make sure to include a MINIMAL, COMPLETE EXAMPLE that can be copy-pasted and shows the
+ bug.
+* If you're having problems with a mesh, you can attach it as a zip file. Make it small!
+* Use [GitHub markdown](https://guides.github.com/features/mastering-markdown/),
+ especially triple-fences for code blocks.
