Convenience extensions on old API, Version 2.0

[Flunzmas]

Hey there,

In my own fork I have made several small convenience improvements in the branch flunzmas_ns3.36 to suit my own requirements:

• added option to specify log modules and log level (changes to old py_interface.py)
• added option to roll back memory upon release (changes to old py_interface.py). Ref: #78
• added option to profile ns3 via perf (changes to old py_interface.py and ns3_util.py, more changes to old ns3_util.py)
• relaxed psutil version constraint (changes to old setup.py)
• added option to only build ns3 on demand (changes part 1 to old py_interface.py, changes part 2 to old py_interface.py)
• several small fixes to get the old master branch version working with CMake. These are probably already fixed by your updates to main and therefore not as important. Ref: #77

Most of them should be unproblematic changes and potentially be useful to others, so I'd like to merge these changes. However, in the meantime you folks have done a lot of awesome new work, to the point where most of the files modified by me don't even exist anymore. I can't properly open a PR on the main branch because I don't yet know where to look for, and have instead opened a PR on the old master branch (#101).

I would be very grateful if you could provide me some guidance in integrating these changes into the main branch and pack everything into a new release that comes with its own commit tag. I think it's reasonable to make it version 2.0 since the API seems very different now.

Thanks for your work!

[Flunzmas]

Hi, has any of the maintainers had the time to look as the proposed changes yet?