Source directory layout reorganisation

[clinssen]

As discussed during the Jülich NEST Hackathon of April 2019.

• Create a new /src directory and move all C++ and sli source files into here. E.g. /nestkernel, /sli, etc. are moved to /src/nestkernel, /src/sli, etc.
• PyNEST/SLI/C++ examples should be combined in /examples
• Create new subdirectories in the /src/models directory according to:
  • stimulating_devices
  • recording_devices
  • spiking_neurons (including precise variants)
  • synapses (maybe we need this also with spiking_, rate_, binary_)
  • binary_neurons
  • rate_neurons
  • gap junctions? dopamine? structural platicity
• PyNEST test suite should not be part of NEST module

[jougs]

This is closely related to #291.

[jougs]

In addition to cleaning things up, this also needs to take into account the FHS and commonly respected practice in the major distributions.

[heplesser]

I generally consider this proposal sensible sensible, although I can never decide if I really like the src directory. Most of our examples are also code of a kind. Topology is going to disappear as a separate entity in NEST3.

[clinssen]

Removed topology module from the list.

[hakonsbm]

Wait until #1282 is merged!

[gtrensch]

@clinssen #1282 is merged.

[gtrensch]

@clinssen Are there any updates on this?

[jougs]

After recent discussions with @terhorstd and others, I am not sure anymore if the first and third point actually have a majority of the developers on their side. We should definitely bring this up again in one of the video conferences. I have a working prototype of the fourth point and the second should also be relatively easy to fix. As I'm working on this already, I'm re-assigning to myself.

[jougs]

The fourth point is now described as the solution to #1130.

[jougs]

As this is more controversial than expected and several points were/are addressed in separate issues, I'm closing this as wontfix.