Number Learning

I'm still playing with number learning models in E.C., but I've been unable to get successful number learning, even with a frontier size of 10,000. I don't think there are bugs preventing learning, *per se*, but if you happen to see anything obvious in the code, let me know.

Instead, I have a couple structural thoughts that might improve learning and better match child cognition:

- Introduce multiple types of tasks, so we're learning to test for equality, construct sets, and name sets at the same time. Right now, I'm only trying to get the model to name sets, and I'm giving it no routines to solve the other two tasks.
- Start from 1, rather than forcing the model to start from 0. If I remember correctly, kids learn 0 later than 1.

I'll give these a try and let you know what I find.