Render oneway roads narrower than twoway roads for the types motorway, trunk, primary, secondary and tertiary.
This is accomplished by making twoway motorways wider and oneway trunk/primary/secondary/tertiary roads narrower.
More important road types are now always rendered wider than less important road types.

Changes:
- Twoway motorways are rendered wider
- Oneway trunk/primary/secondary/tertiary roads are rendered narrower
- Secondary is now narrower on z13/z14
- Tertiary_link is now rendered just like tertiary
- Round line caps on tertiary and larger are removed on regular roads to prevent gravitystorm#83
All other road types are rendered as before.

Further changes to the width of link roads are left for a future pull request.

I tried to achieve the goal of making more important road types wider than less important ones while at the same time making as little changes to the roadsizes as possible. I think it would be worth for if someone with feeling for design has a closer look at the sizes as we have them now. It should be very easy to adapt now: one can just change the variables in the beginning of the style.

I put the road sizes in a kind of table to make them more legible. If people think that's not practical, I can change it back to a list again.

This pull request resolves gravitystorm#265 and gravitystorm#83 on Github and 1952 on trac.

…l ones

Correct typo.