On Windows absolute path inside xdmf to hdf was incorrect. Fix to relative path because file must be transferable

This mv one dependency from _neighbors from the
base class Element to the class TemplateElement.

Moving code from the constructor.

Remove no longer required default constructor.

This simplifies most of the code.

warning: uninitialized record type: 'pyramid_nodes' [cppcoreguidelines-pro-type-member-init]

Dmitri Naumov authored 3 years ago and Tom Fischer committed 3 years ago

spdlog is linked "public" in BaseLib.

Reason is the violation of odr for some globals defined
in the spdlog library.

==1540297==ERROR: AddressSanitizer: odr-violation (0x7f5ea9c9d020):
  [1] size=40 'vtable for spdlog::spdlog_ex' _deps/spdlog-src/src/spdlog.cpp
  [2] size=40 'vtable for spdlog::spdlog_ex' _deps/spdlog-src/src/spdlog.cpp
These globals were registered at these points:
  [1]:
    #0 0x5614686e0dfa in __asan_register_globals.part.0 (/home/naumov/w/ogs/d/bin/ogs+0x1bfdfa)
    #1 0x7f5e6cdbe7eb in asan.module_ctor (/home/naumov/w/ogs/d/bin/../lib/libMeshLib.so+0x17d37eb)

  [2]:
    #0 0x558bd62b6dfa in __asan_register_globals.part.0 (/home/naumov/w/ogs/d/bin/ogs+0x1bfdfa)
    #1 0x7f831c7e54ab in asan.module_ctor (/home/naumov/w/ogs/d/bin/../lib/libBaseLib.so+0x89a4ab)

This change makes it possible to use MPI related mesh IO functionality without initializing PETSc.

Using (const) access functions in two cases of direct
member access.

Move common setID() member from derived classes into
the base class allows for making the _id member private.

Access through getID() in two occasions for in gmsh and gocad
IO interface functions.

Simplifies handling in CMake. Just link to petsc-target.