add non us specific 'meter' spelling support for buffer unit.

[mdwragg]

Added ability to specify buffer units in US and non-US spelling of 'meter' (i.e. 'metre').

[morganherlocker]

Is this common in other packages? The spelling is clearly stated in the docs. I'm not totally opposed, but I'm wary that this may be a slippery slope for supporting multiple dialects all over the place.

[mdwragg]

I couldn't say for sure if it is common or not in other packages. Though, the SI unit states the spelling is 'metre'. And the only country on this fair planet that uses the spelling 'meter' is the United States.

When I worked for Smallworld (GIS) we would certainly accept both forms, though that software was predominantly written in the UK.

http://grammarist.com/spelling/meter-metre/

"The metre or meter (American spelling), (SI unit symbol: m), is the fundamental unit of length (SI dimension symbol: L) in the International System of Units (SI), which is maintained by the BIPM."

Your call I guess - it certainly caused me to slip up (I'm British, living in the US, so used to knocking into words spelt differently...). Depends on how kind/slick you want the developer experience to be.

Others seem to get around such issues by taking just the unit symbol 'm' (OpenLayers, for instance).

[morganherlocker]

ok, i'm sold :)

[tcql]

@morganherlocker we would also want to update grids and the like to accept kilometres, no?

[morganherlocker]

Ideally, we would have a units enum in the turf typedefs https://github.com/Turfjs/turf-www/blob/master/typedefs/geojson.js that would provide a set of available options. I believe the grids all derive their units from turf-distance and turf-destination, so only those two would need to be updated.