Render names on junctions

This renders names of junction=yes and junction=roundabout.
Rendering is similar to highway=motorway_junction.
Change junction rendering

* Also render name for traffic_signals without junction tag
* Don't render junction names on roundabouts
* Render junctions in black and in a smaller font
* Offset junction names only when the traffic signal icon shows
* Start rendering junctions from z14
* Wrap lines
Merge pull request #813 from math1985/crossroad-names

Crossroad names