Large refactoring between the Lesson 30 of part 1 and part 2

[ianchanning]

There appears to have been a large refactoring of the code between the last lesson of part 1 and the start of part 2. Everything has been split out into separate files and switched to using npm rather than importing all the code directly.

It means anyone who hasn't paid for the course has a harder time following along. Not that this is a major issue, but worth mentioning for the community notes, that is you can't expect just to pick up exactly where the previous course left off.