add disease template for part 1

part_1_disease/.gitignore

part_1_disease/CMakeLists.txt

part_1_disease/README.md

part_1_disease/configExample/disease_in.ini

part_1_disease/examples/deterministic/disease_in.ini

part_1_disease/examples/single_population/disease_in.ini

part_1_disease/include/INIReader.h

part_1_disease/include/doctest.h

part_1_disease/simulation/main.cpp

part_1_disease/simulation/simulation.cpp

part_1_disease/simulation/simulation.h

part_1_disease/simulation/test.cpp