Create ElementData() function as in mathics project

[Axel Kramer]

Read in chemical elements data form CSV file: https://github.com/mathics/Mathics/blob/master/mathics/data/element.csv

and create ElementData() function.

See: https://github.com/mathics/Mathics/blob/master/mathics/builtin/physchemdata.py

[Axel Kramer]

Commits d62717e and 09ca2dc improve ElementData() function.

Please help reviewing the data and improving documentation ElementData.md

[Axel Kramer]

Please use the Github issue tracker to open a new issue if this issue shouldn't be closed Github issues