[Tagging] Implied oneway tag for highway=*_link, wiki edits

[Richard Bullock]

> Paul Johnson wrote:
>> Name one road type which is inherently one-way.
>>
> Roundabouts, Motorway slip roads in the UK,  half of a dual carriageway,
> bus guideways...

Here's a 2-way motorway sliproad in the UK. It's not the only example

http://maps.google.co.uk/?ie=UTF8&t=k&ll=52.035309,-2.162185&spn=0.001162,0.002401&z=19

We even have 2-way single-carriageway sections of motorway mainline as well.

Roundabouts I agree with are oneway (actual roundabouts, not just any old 
circular road) - and roads like the Magic Roundabout in Swindon et. al. are 
not single roundabouts.