Merge remote-tracking branch 'origin/master' into IvanChanges
A bit of refactor
some strange results for newton method: where should we put the convergence criterion?
Changed convergence criterion. See extensive comment in function.
additional change of convergence criterium. Able to handle most cases correcly.
Some refactor
Merge remote-tracking branch 'origin/IvanChanges'

Conflicts:
	Worksheet 2/calculate_errors.m
	Worksheet 2/derive_G_implicit_euler.m
	Worksheet 2/error_norm.m
	Worksheet 2/explicit_euler.m
	Worksheet 2/implicit_euler.m
	Worksheet 2/newton.m
	Worksheet 2/plot_numerical_solutions.m
	Worksheet 2/solve_with_numerical_method.m
	Worksheet 2/worksheet2.m
	Worksheet 2/write_errors.m