updated and added 3 tutorials

[MichaelTrann]

1. Electrophysiological Time-Series - added section about sampling, ground vs reference. still need section about burstiness/bands

Event Related Potential Tutorial - fixed syntax errors to make compatible with python 3, overall solid tutorial by Torben, not sure what else to add

Filters - fixed syntax errors to make compatible with python 3, overall solid tutorial by Torben, not sure what else to add

Note: this is in partial fulfillment of #1

[ArcadeShrimp]

These all look good - I dont see any conflicts between our tutorials. Tutorial 1 seems to have an empty 'Neural Oscillations' section at the end

[sydney-smith]

1 Electrophysiological Time Series

Looks good and I really like your non-neuro explanation of sampling and use of external resources. However, I think it could benefit from a title at the beginning and a brief introduction about electrophysiological sampling/a short summary of what the tutorial is going to be about. Maybe a little more organization. For example, it's not clear why "Plot the Time Series" is labeled with the number 1. Also, I look forward to reading your added sections on bursting and bands!

2 Event-Related Potential Tutorial

Looks great!

4 Filters

Fix IndexError on ln[7]. I would try to do something like this:
delta_funct[int(len(delta_funct)/2)] = 1
Looks good!