Hardening/testing spec v0.1.1

[stevencarlislewalker]

• [x] Clean tests and ensure they are passing
• [x] Create passing test of simulation of variant model with many break points
• [x] Create passing test of calibration of variant model with many break points and some multipliers that need to be estimated
• [x] Tidy up macpan.cpp and create and push McMasterPandemic.cpp
• [x] Merge main into tmb