Adaptive FEM for Poisson problem

This is the starting code for laboratory number 7 of the course "Theory and Practice of Finite Element methods".

We solve the Poisson problem

[ \begin{split} -\Delta u &= f \quad \text{ in } \Omega\ n\cdot \nabla u &= g_N \quad \text{ on } \partial\Omega_N\ u &= g_D \quad \text{ on } \partial\Omega_D \end{split} ]

on convex and Lipschitz domains $\Omega$, using the Finite Element method, and the deal.II library (www.dealii.org).