Quantity __init__ method now uses a variable number of arguments.
Quantity __init__ method now uses a variable number of arguments.

This will be more useful for reading input files, where we are printing
this information as a tuple rather than as a Quantity object.

faribas/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,nyee/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,KEHANG/RMG-Py,comocheng/RMG-Py,KEHANG/RMG-Py,nickvandewiele/RMG-Py,chatelak/RMG-Py,enochd/RMG-Py,faribas/RMG-Py,comocheng/RMG-Py