Merge branch 'ci/centralize-config-2.6' into 'releases/2.6'

See merge request [!111]

  [!111]: Nonecore/dune-localfunctions/merge_requests/111

Merge branch 'feature/remove-difforder' into 'master'

See merge request !96

[bugfix] remove last traces of diffOrder

See merge request !91

(cherry picked from commit f9dfb028)

3510c6e4 [bugfix] remove last traces of diffOrder

Merge branch 'bugfix/reduce-testgenericfem' into 'master'

See merge request !102

[test] reduce number of different polynomial degrees in testgenericfem

Closes #9

See merge request !101

(cherry picked from commit 7c82255b)

f76a0671 [test] reduce number of different polynomial degrees in testgenericfem

Merge branch 'feature/document-removal-of-clone' into 'master'

See merge request !99

Merge branch 'feature/fix-changelog-markdown' into 'master'

See merge request !100

Document the removal of the clone() methods

See merge request !98

(cherry picked from commit a3663335)

fe7067e1 [doc] Document the removal of the clone() methods

[doc] Fix markdown

See merge request !97

(cherry picked from commit e86aaa16)

5243a5b4 [doc] Fix markdown

Merge branch 'feature/require-cmake-3.1' into 'master'

See merge request !95

[cmake] Require CMake 3.1 similar to dune-common

See merge request !94

(cherry picked from commit 525bbef9)

a1ffffcf [cmake] Require CMake 3.1 similar to dune-common

Merge branch 'feature/remove-difforder' into 'master'

See merge request !93

[bugfix] remove further traces of diffOrder

See merge request !92

(cherry picked from commit 532a21fe)

9c7e9f9a [bugfix] remove further traces of diffOrder

Merge branch 'feature/test-finiteelementcache' into 'master'

See merge request !88

Merge branch 'cleanup-qklocalbasis' into 'master'

See merge request !87

Merge branch 'test-localfe-clone' into 'master'

See merge request !86

Merge branch 'remove-difforder-completely' into 'master'

See merge request !85

Merge branch 'test-shapefunction-duality' into 'master'

See merge request !84

add test for finite element caches

See merge request !68

(cherry picked from commit 4b89dad6)

81533dea [test] write test for finite element caches
a099244e Remove left-over uses of FixedOrderLocalBasisTraits

Cleanup qklocalbasis

See merge request !67

(cherry picked from commit 2a184eeb)

30dad5b5 Remove unused private member
6af4903a Simplify the 'partial' method of QkLocalBasis
e61ab11c Implement second partial derivatives for QkLocalBasis

Test whether LocalFiniteElement has the 'clone' method

See merge request !66

(cherry picked from commit 8f3fccf9)

5fb4cadf Test the LocalFiniteElementVirtualInterface::clone method
23ced931 Remove 'clone' methods from the LocalFiniteElement implementations

Remove the diffOrder parameter completely

See merge request !63

(cherry picked from commit bf4db820)

57e59a66 Remove the diffOrder parameter completely

Test shapefunction duality

See merge request !62

(cherry picked from commit adb16631)

546930ea Remove redundant LocalInterpolation test
f6a0792b Rewrite testLocalInterpolation to match Ciarlet's definition

Revert "Merge branch 'bugfix/added-changelog' into 'releases/2.6'"

See merge request !82

Merge branch 'modernize-raviart-thomas-elements' into 'master'

See merge request !83

Modernize the Raviart-Thomas implementation a bit

See merge request !74

(cherry picked from commit 72699092)

9dea9719 Test the RT0Cube2DLocalFiniteElement class
39634be9 Fix a bug in RT0Cube2DLocalInterpolation
07d7e196 Fix various bugs in RT02DLocalFiniteElement

This reverts merge request !72

Merge branch 'fix/refelem-by-value-in-rannacher-turek' into 'master'

See merge request !79

[RannacherTurek] Adapt to new reference elements.

See merge request !76

(cherry picked from commit 88d58715)

ecf774eb [RannacherTurek] Adapt to new reference elements.

Merge branch 'fix/refelem-by-value-in-edge-elements' into 'master'

See merge request !77

[Edge] Use reference elements by value.

See merge request !75

(cherry picked from commit 91b80d27)

e9acb599 [Edge] Use reference elements by value.
97db7ed4 [Edge] Get a new reference element each time the element is constructed.

Bugfix/added changelog

See merge request !72

Merge branch 'bugfix/dont-convert-refelement-to-reference' into 'master'

See merge request !70

[bugfix] do not assume `ReferenceElement::general` returns a reference

See merge request !69

(cherry picked from commit 043a6bf3)

e172ca4d [bugfix] do not assume `ReferenceElement::general` returns a reference

.gitlab-ci.yml: build against releases/2.6 branch of other modules

See merge request !64