added exercise 3 solution

examples/lanczos/Lanczos.ipynb

exercises/ex03_solution/TFIM_time_evolution/cpp/Makefile

exercises/ex03_solution/TFIM_time_evolution/cpp/plotmagn.py

...ion/TFIM_time_evolution/cpp/trFieldIsingTimeEvolution.cpp

...lution/python/.ipynb_checkpoints/trising-checkpoint.ipynb

...es/ex03_solution/TFIM_time_evolution/python/trising.ipynb

...cises/ex03_solution/TFIM_time_evolution/python/trising.py

...3_solution/TFIM_time_evolution/python/trising_skeleton.py

...scattering/.ipynb_checkpoints/scattering-checkpoint.ipynb

exercises/ex03_solution/scattering/scattering.ipynb