[Tagging] highway=unclassified

[Nathan Edgars II]

If there was any practical difference between residential and 
unclassified, the TIGER import ignored that in the US by using 
residential for everything unimportant. So when I map I treat 
residential as unclassified with mainly residential abutters, and will 
sometimes change TIGER residentials to unclassified if they're clearly 
not residential. But there's definitely no difference in where they fit 
in the classification in the US.