Adding an avg function

[thedadams]

I have run across a couple instances where it would have been beneficial to have an avg (average) function on lists, similar to the sum (for numbers) and product functions.

Would there be any interest in adding such a function?

I would be happy to do the work and submit a PR, but wanted to start a discussion as suggested before creating the issue and PR.

[blacksmithgu]

avg is equivalent to sum(list) / length(list), right?

[blacksmithgu]

I've added average as a function in beta 0.5.49.

[thedadams]

Oh, awesome! Thanks for the quick response.