* initial partial API

* nrnpy_set_pr_etal should be extern C

* nrn_call_function leaves results on stack

* segments, properties

* including hocdec.h to try to avoid Datum errors on some systems

* sectionlist and allsec hoc_Item getters

* symbol and object introspection

* symbol table getting and interating

* object ref, push

* Renamed files to avoid having two nrnapi.h files.

On some systems (most? but not the one I used for everything else),
some files tried to include the wrong nrnapi.h during the
"make install" phase.

* neuronapi.cpp no longer uses its .h, that is now a header for 3rd party tools

* switched to enum for stack types

* needed typedefs for C to be happy

* test: sections.c

* clang-format

* replaced hoc_Item with new synonym nrn_Item

* netcon example shows no need for dlsym

* support for .so files in addition to .dylib

* removed an excess const

We'll still treat the pointer as const, but the user has no reason to care.

* Add Robert's API tests to CTest (#2365)

* build + run tests

* fixups

* different fixup

* add -rdynamic

* bugfix flagged by ASan

* fix to header file name of api

* hh_sim and sections work with handles
don't have quantitative identity with the old hh_sim results, but very
close.

* rename stack_types_t per @olupton

* replace param_handle with param

* working vclamp

* unified API property functions

* getters use const args

* forgot to commit sections

* vector_capacity now on const obj

* Several improvements

 - C/C++ api header included in implementation
 - signatures made compatible
 - public nrn_Item defined as inheriting from hoc_Item
 - dropped overlapping definitions. types are both fw declarations and
   opaque types

* Make tests link against nrniv_lib, no dlopen

* Address sonar lint reservations

* Make comparisons be part of the test and account for fp innacuraciesa

* Tests to find ref files

* api: Make tests resilient to accumulated errors

* Use in-test ref result, depending on NRN_ENABLE_CORENEURON

* Use free for allocated c strings

* Dont alloc Section Item to heap as its not used.

NOTE: It seems that Sections are never freed. However we are
lacking API to free Sections and Symbols in general.

* Address intel compiler complain

* Free memb_func[].dparam_semantics

* Switch dparam_semantics to unique_ptr (no raw!)

* Memb_list to do its memory management

* Memb_list to be aware of its potential "view" condition and not free

* Back pdata free

* nrn_init to better initialize mpi

* Addressed a number of warnings, inc avoidiing potential double free

* Addressed sonarcloud issues

* fix the merge with master

* Fix test/api/netcon.cpp after merge with master

  - after RANDOM construct (#2627) was merged,
    netstim.mod uses Random123 by default
  - before this, netstim was using scoprand by default
    and reference results were from the same
  - now, explicitly use Random123 in the test and update
    reference results

* fix warning [-Wimplicit-exception-spec-mismatch]

---------

Co-authored-by: Olli Lupton <oliver.lupton@epfl.ch>
Co-authored-by: Fernando Pereira <fernando.pereira@epfl.ch>
Co-authored-by: Pramod Kumbhar <pramod.s.kumbhar@gmail.com>
Co-authored-by: Nicolas Cornu <nicolas.cornu@epfl.ch>
Co-authored-by: Michael Hines <michael.hines@yale.edu>