Fix bug in Longitude definition

[albertemmerich]

As found by @INOPIAE there is an bug in spec 7.0.17 chapter 2.16.
The definition of Longitude is
Longitude = ("N" / "S") upto180 [ "." 1digit]
but should be
Longitude = ("E" / "W") upto180 [ "." 1digit]
The text in the chapter is correct.

[tychonievich]

Thanks for catching this!

Because this is an error in the machine-readable part of the spec. I think per the specification's policy on version numbers, that would mean rolling out v7.0.18, though I suppose we could do a hot fix to 7.0.17 instead.