* Added physical pressure units
This uses tuple pair which stores units required to be converted to respective other units as mentioned.
Available Units:- Pascal,Bar,Kilopascal,Megapascal,psi(pound per square inch),inHg(in mercury column),torr,atm
* Formatted file
File was formatted as per repo rules
* Reformatted file :)
* Added more reference
* More reference added
