Test whether vectors export 'reference' and 'const_reference'

See merge request !111

[feature][SeqILU] faster implementation of ILU preconditioner

See merge request !96

Implement the method 'setSize' for BDMatrix and BTDMatrix

See merge request !110

These are standard types from the STL.  Apparently all dune-istls
vectors do export them.

Test the method BCRSMatrix::setSize

See merge request !109

Implement construction of BDMatrix from std::initializer_list

See merge request !108

.gitlab-ci.yml: update environments

See merge request !106

resolve ambiguous call by explicitly calling `Dune::Hybrid::size`

See merge request !107

Reference: core/dune-common#77

- Added:   Debian 10 with gcc in C++17 mode
- Removed: Debian 8 + Backports with clang

Reference: http://lists.dune-project.org/pipermail/dune-devel/2017-July/002224.html

[GeneralizedPCGSolver] Increment iteration counter for all verbosity levels

See merge request !105

This commit fixes Issue #32

default.

simple Compressed Row Storage for the lower and upper triangular
matrices. Also, SeqILU unifies both, SeqILU0 and SeqILUn.

[bugfix][cmake] install allocator.hh

See merge request !103

Commit 8da92ce1 added allocator.hh but
forgot to add it to the installed headers in CMakeLists.txt.

[multirhstest] Check with AlignedNumber.

See merge request !87

[Fix] Update mailing lists addresses.

See merge request !100

Add `data()` accessor methods

See merge request !99

Feature/support mingw

See merge request !88

[dynamic polymorphism] use #if instead of #ifdef for the guard

See merge request !95

we add a compatibility layer, when
DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE is enabled. We now ise #if
instead of #ifdef to check for the flag and add the switch to
scalar-product interface class.

fix the cmake magic to enable backwards compatibility for the category interface

Closes #29

See merge request !94