[test][el1p] Replace deprecated IOFields::init with initOutputModule

See merge request !1297

Feature/md explicit assembler

Closes #521

See merge request !1288

[fix][mpfa][fvgridgeom] rearrange public aliases

Closes #597

See merge request !1293

[nonequilibrium] fix typo in volume variables

See merge request !1295

Apparently, this isn't tested.

[fix][multidomain] linker error with c++14

See merge request !1294

This is necessary for the upwind scheme in facet coupling models, as
the upwind/downwind volume variables type can be from the other domain.

The code in the implementation is basically just a copy
of the ccexplicitlocalassembler. The only difference is
how the current solution is obtained.
TODO: can we reuse code here?

This function is basically just a forward to evalLocalResidual() and
obtaining the first entry. Since this entire header only deals with
cc schemes we can also write out this call in the occurrences. This
is actually also how we do it in the standard cc local assembler.

clang3.8 threw a compiler error because it couldn't extract the
types from the fv grid geometry within the helper class. Putting
the helper after the other types (that are tried to be extracted
within the helper) solved this issue.

Feature/update coupling context staggered

See merge request !1200

[CMake] Added labels for freeflow and rans tests

See merge request !1291

[test][md][label] Add multidomain label to multidomain tests

See merge request !1289

[discretization] Rename header methods.hh to method.hh

Closes #572

See merge request !1287

Cleanup/md remove setcouplingmgr

Closes #564

See merge request !1285