Split "test instances" from generic code

[MichaelClerx]

Eventually, we might envisage functional testing as some reusable tool.
But before that, I think we'll benefit from having a clearer separation between the two

I'd propose something like this:

• Move the tests outside of the main module.
  • Each test will then start with something like "import functional_testing",
  • then define a class that implements an interface class MyTest(functional_testing.Test),
  • then have some methods that return a predetermined type.
  • These methods of course can use shared utility functions e.g. functional_testing.do_common_thing(...)
• Move the list of tests outside of the main module.
• Move part of the thing that knows how to store stuff outside of the main module (<-- this idea needs a bit of work)

Then, at some point, we should see lots of commits to this "user-specific" directory, and very few to the main code, and then we can consider making a full split :D

The main benefit in the short run is that PINTS devs can just look in the "user-specific" directory and play around there, without having to navigate the more complex generic code