Remove interface compatibility in the rest

[alarshi]

No description provided.

[tjhei]

/run-tests

[tjhei]

Awesome, this is so much nicer. As in #1679, consider editing the "author" of your commits. You also have quite a few commits including merge commits in this PR. Maybe you can squash your commits? (ask one of us for help if needed)

[tjhei]

Also please rebase to the newest master. That should fix the test.

[tjhei]

There are some errors, for example:

/home/dealii/source/tests/tangurnis.cc:60:65: error: ISO C++ forbids declaration of ‘evaluate’ with no type [-fpermissive]
                  MaterialModel::MaterialModelOutputs<dim> &out) const
                                                                 ^~~~~

/home/dealii/source/tests/prescribed_velocity_boundary.cc:166:54: error: ‘p’ was not declared in this scope
               const double r2 = ( pos[0] - 1.0 ) * ( p[0] - 1.0 ) + ( p[1] - 1.0 ) * ( p[1] - 1.0 )
                                                      ^

[alarshi]

Aa oo. I just did a hard reset on my master to the development version.
I didn't test the 'tests' folder. I am making individual branches for all files and will submit pull request for each. Thank you!

[bangerth]

In reference to #1538.