Restructure code to improve maintainability

[smangham]

Currently, maintaining or editing the material is a little difficult, as changes in one section carry forward to changes elsewhere. It would help a bit more if the changes in each section were more isolated - so that each section's changes could be implemented as a separate branch, making it easier to do.

The files that are touched are:

1. Collaborative Development
   • 1.4: inflammation/models.py: Minor edit just to demo git.
   • 1.5: inflammation-analysis.py, inflammation/models.py: Improving code quality.
   • 1.6: inflammation/models.py, inflammation/views.py: Improving code quality (nonspecific).
2. Ensuring Correctness
   • 2.1: tests/test_models.py: Expanding tests for models.
   • 2.4: tests/test_models.py, inflammation/models.py: Expanding tests, fixing errors in patient normalisation.
3. Software Development as a Process
   • 3.2. full-data-analysis branch: Adds new code for running analysis.
   • 3.3: inflammation/models.py: Adding new data source.
   • 3.3: inflammation/compute_data.py, tests/test_compute_data.py: Refactoring to class-based load.
   • 3.4: inflammation/compute_data.py, test/test_compute_data.py: Refactor analysis to allow regression testing.
   • 3.5: inflammation/compute_data.py: Refactoring into MVC model.
4. Development for Re-Use
   • 4.1: feature-std-dev branch: Adds new code for plotting standard deviation.
   • 4.1: inflammation-analysis.py, inflammation/models.py, test/test_models.py: Editing the submitted code.
5. Managing Software
   • Nothing specific.

My proposal would be to replace inflammation/models.py with a submodule, inflammation/models. Then when we add a new data source, we can do it by only editing one file, e.g. inflammation/models/csv_data.py. Likewise, splitting tests into separate files per module. This could be done either by starting with it split up, or splitting it into multiple files as part of section 3.