Provide code/snippet to load model parameters

[tarelli]

We need snippet to load netpyne model paramters or the original HNN ones

[salvadord]

to load original .param files: use hnn repo utils.py setCfgFromFile() func

[salvadord]

to load netpyne simConfig: sim.loadSimConfig(filename)

[salvadord]

to load netpyne simConfig directly from json:

with open('filename.json', 'r') as f: 
 cfg=json.load(f)

import specs
hnn_cfg = specs.SimConfig(cfg)