[new-unit] Torque in pound-force inch

[adrianinsaval]

Description Sometimes bolts torque specifications come in lbf·in and some tools use this too. I've needed this unit conversion many times before.

Units to be added

Unit name	Property	Reference to the conversion formula
Pound-force inch	Torque	https://www.google.com/search?q=N%C2%B7m+to+lbf%C2%B7in