Model.train() needs a refactor

[oadams]

The stopping criteria and nesting of are getting unwieldy and bugs are likely to creep in. It's also quite long and could be broken down.

[shuttle1987]

The train method seems like it's very long and perhaps doing a bit too much in the one method. I'd need some info as to where the code can be split though. For a start I feel like the training and file handling could be in separate methods here.

[shuttle1987]

I'd be happy to pair program a bit on this one to get this cleaned up, let me know if you are keen.

[oadams]

Sounds good, let's do it.

[shuttle1987]

I've cleaned this up a bit in #147, specifically I have moved to using context managers for a few things so that handling the closing of files and sessions is easier. It has made the nesting one level deeper in places though, but overall I think it's less complex.

[shuttle1987]

I feel like when #154 is closed we can close this issue.