Fix nomenclature according to tutorial

Closes #13

See merge request jfahl_01/pacxx-projectseminar-2019!20

Closes: #13

Import built tutorial from dune-pdelab-tutorials

Closes #12

See merge request jfahl_01/pacxx-projectseminar-2019!19

Closes: #12

Don't use std::vectors inside local operators

Closes #5

See merge request jfahl_01/pacxx-projectseminar-2019!18

The local basis is passed into the local operator kernels as a const
reference.  That means, its lvalue is not a constant expression.  Would we
pass it by value, then it's lvalue would be a constant expression (through
it's rvalue still would not).

Calling a static function of a class throuh an object with the syntax
```c++
  lb.size()
```
will evaluate the lvalue of the object.  Since that lvalue is not constant
when the object was passed by reference, the call cannot be a constant
expression.

Clang (rightly) complained about this, so write the call as
```c++
LocalBases::size()
```
where a constant expression is required.

We don't use it anymore

This uses our own Q1 local basis implementation that hands out std::array
results

Imported and adapted from dune-localfunctions q1localbasis

Avoid allocating extra vector in matrix-free applyscaleadd()

Closes #4

See merge request jfahl_01/pacxx-projectseminar-2019!17

This is to appease clang 3.8

Implement jacobian_apply_volume analytically

See merge request jfahl_01/pacxx-projectseminar-2019!12

Closes: #4

Implement jacobian_apply_boundary() analytically

See merge request jfahl_01/pacxx-projectseminar-2019!16

Addresses: #6

Check the number of iterations needed by newton

Closes #11

See merge request jfahl_01/pacxx-projectseminar-2019!15

Closes: #11

Fix warnings in debian-9 clang build

See merge request jfahl_01/pacxx-projectseminar-2019!14

Addresses: #3

Clear result in matrix-free operator apply()

Closes #10

See merge request jfahl_01/pacxx-projectseminar-2019!13

At the operator level, apply() is the equivalent of mv(), not umv().

Closes: #10

Run CI with PACXX

Closes #8

See merge request jfahl_01/pacxx-projectseminar-2019!11

Make test definitions more readable (also for octagon)

See merge request jfahl_01/pacxx-projectseminar-2019!10

Make test definitions moare readable

See merge request jfahl_01/pacxx-projectseminar-2019!9

Addresses: #9

Use an octagon domain to have something better than unit square

Closes #7

See merge request jfahl_01/pacxx-projectseminar-2019!8

Addresses: #9

Fix config key name for grid reader type

See merge request jfahl_01/pacxx-projectseminar-2019!7

Make Ini file configurable

See merge request jfahl_01/pacxx-projectseminar-2019!6

Make the operator really matrix-free

Closes #2

See merge request jfahl_01/pacxx-projectseminar-2019!5

Closes: #2