Ned Coltman authored Apr 29, 2022 and Timo Koch committed May 02, 2022

* Update the generators for the new spatialparams classes
* use the new problem and spatialparams classes

[2p2c][doc] rewrite model documentation

See merge request !3056

[script/handbook] update release branch in script

See merge request !3082

[bugfix][parallel][solver] Rebuild parallel helpers after grid adaption

See merge request !3080

[tpfa][gg] Make sure hasBoundaryScvf_ is properly reinitialized in update

See merge request !3078

Provide defaults for FluxVariablesCache and FluxVariablesCacheFiller

Closes #867

See merge request !3077

The former checks whether a property is specialized for the given typetag,
The latter are convenience alias to get the defined type if it's
specialized for the TypeTag and some other given type if not.

[version] Bump version to 3.6-git

See merge request !3076

Feature/headercheck

See merge request !3064

Update changelog

See merge request !3073

[material][pnm] Fix position of deprecated attribute

See merge request !3071

[readme] Update pipeline link to release 3.5

See merge request !3070

[ci] Try to improve stage names

See merge request !3068

Cleanup/cmakelists

See merge request !3066

[doc] add equations of geomechanics models in doxygen

Closes #1139

See merge request !3042