2.14.5: Make {{lang}} available in the template?

[Moonbase59]

Considering #37, it would be nice to be able to use {{lang}} in the template, too, for instance to use the lang attribute, or at least create YAML like this:

---
# {{notice}}
dictionary: {{lang}}
word: "{{word}}"
---

so the dictionary notes could later be evaluated using Dataview, for instance.