`import neuron` modifies the `help` pager

[JCGoran]

In Python, when calling help([OBJECT]), one usually gets the scrollable help (via less or some other program). This seems to stop working upon running import neuron, and all subsequent calls to help will be placed on stdout instead.

Affected versions: both stable (currently 8.2.4, installed from PyPI) and master.

To reproduce:

>>> help(list) # should use a pager
>>> import neuron
>>> help(list) # no longer using a pager

The relevant code seems to be here: https://github.com/neuronsimulator/nrn/blob/master/share/lib/python/neuron/doc.py#L40-L79