Cleanup and minor bug fixes

CMakeLists.txt

README.md

examples/modular/force_reduction.py

examples/modular/sphere_box_global.py

examples/modular/spring_dashpot.py

runtime/pairs.hpp

runtime/timers.hpp

src/pairs/__init__.py

src/pairs/analysis/devices.py

src/pairs/code_gen/cgen.py

src/pairs/code_gen/interface.py

src/pairs/mapping/funcs.py

src/pairs/sim/cell_lists.py

src/pairs/sim/domain_partitioning.py

src/pairs/sim/load_balancing_algorithms.py

src/pairs/sim/simulation.py