Update merged gws

[MaxvanderWerf]

Updated the merged_gw.csv files of 16/17, 17/18 and 19/20 by adding a position column.

What I did:

• Player names are formatted (f.e. from 'Xherdan_Shaqiri_462' to 'Xherdan Shaqiri')
• Player names are decoded (f.e. from André Schürrle to Andre Schurrle)
• Players with less than 10 minutes played in the entire season are deleted from the dataset
• Secondary FPL data is scraped from Statsbunker
• Statsbunker data is cleaned to make sure the names are the same as in the original data
• Statsbunker and original data is merged to add positions to original datasets
• In the end every player's position is added to the dataset except for those with <10 min played (their position is NaN)

Attached you will find the jupyter notebook with Update older datasets.pdf the code.