Export element type  in FV element geometry

See merge request !2132

Fix/staggered upwindfluxvars

See merge request !2133

cleanup/staggeredupwindfluxvars ifconstexpr

See merge request !2127

[freeflow][staggeredupwindfluxvars] reduce the doLateralMomentumUpwinding_ functions with if constexpr

[freeflow][staggeredupwindfluxvars] reduce the getLateralUpwindingMomental_ functions with if constexpr

[freeflow][staggeredupwindfluxvars] reduce the getFrontalUpwindingMomenta_ functions with if constexpr

[freeflow][staggeredupwindfluxvars] reduce the doFrontalMomentumUpwinding_ functions with if constexpr

[cleanup] Remove unused typedefs

See merge request !2124

Use Markdown for auto-generated README.md

See merge request !2121

Cleanup rans tests with c++17

See merge request !2119

[cleanup][2p] Remove include of 1p model

See merge request !2122

[docu][doxygen] Change dot image format from png (default) to svg to reduce...

Closes #835

See merge request !2123

[docu][doxygen] Change dot image format from png (default) to svg to reduce the size of the doxygen html folder to less than 40 percent.

Although `extractmodulepart.sh` generates a `README.md`, no
Markdown is used so far in this file. Use Markdown to define
headings, lists and a table.

[facet][box] do not use modified elembctypes

See merge request !2115

[fix] Update cmake install headers

See merge request !2117

[changelog] Comment on support for pre 2.12

addresses comment in #827

See merge request !2116