Testsuite: tests should not output and compare initial and final residuals

[tamiko]

We have a number of tests that output inital and final residuals and iteration count. Exemplarily,

DEAL::  Solving linear system
DEAL::Starting value 1.67096
DEAL::Convergence step 9 value 2.69526e-13
DEAL::   Solved in 9 iterations.

This is an issue because the exact floating point number for the initial and final residual, as well as the number of iterations typically depends on library versions, operating system, hardware and processor architecture, and what optimization have been chosen. We should avoid printing these numbers

(As a side note: the final residual in above output isn't critical - we ignore it thanks to our numdiff settings. Typically a test fails because the initial residual or the number of convergence steps differ.)

Instead one possiblity is to use the check_solver_within_range macro that can be invoked for example as follows:

check_solver_within_range(solver.solve(A, u, f, preconditioner),
                              control.last_step(), 40, 44);

and will output success if the solve() converged within 40 to 44 steps and otherwise outputs a failure condition.