force UTF8 encoding on ogr2ogr

leaving out --config SHAPE_ENCODING UTF8 breaks some special characters which is not a big deal since the name column isn't used by the style anyway, but we don't want people to be irritated by an ogr2ogr warning.
Fix living_street on z12

Render highway=living_street on z12 like residential roads instead of
wider
Render tertiary_link in correct color

This resolves #406.
Correct widths of bridges and tunnels for primary

The definitions for bridges and tunnels were the wrong way around.

This resolves #404.
Fix bridge rendering of service ways

Add the correct line-cap.

This resolves #402.
Correct zoomlevel living_street

Apply 1px-grey rule on living_street to z12 instead of z13
Bring zoom references in line with coding standard

Replace [zoom=13] with [zoom >= 13][zoom < 14]
Cleanup oneway and railway=spur/siding in SQL

- The tag railway=spur/siding is no longer rendered. Please use highway=rail,
  service=spur/siding instead. This resolves #367.
- Rationalise oneway scoping in queries. This resolves #368.
Use layer tag of tunnels for rendering

The layer tag is not taken into account for the rendering of tunnels.
In other words, overlapping tunnels on different layers are now
properly ordered. This is done by using group-by.
Clean up definition tracks

The track definitions used to be rather inconsistent. The following
changes make the definitions more consistent across bridges, tunnels,
and normal roads.

- Give tracks without tracktype the same line-opacity as tracks with tracktype;
- Give grade3 tracks on bridges or in tunnels the same line-opacity as regular grade3 tracks;
- Give grade3 tracks on bridges or in tunnels dashes, just like regular grade3 tracks;
- Give grade2 tracks on bridges or in tunnels same dashes as regular grade2 tracks;
- Give grade3 tracks no wider white background in tunnels than on regular grade3 tracks.
Merge branch 'living_street-z12' of https://github.com/math1985/openstreetmap-carto into math1985-living_street-z12
Merge branch 'service-bridge-linecaps' of https://github.com/math1985/openstreetmap-carto into math1985-service-bridge-linecaps
Merge pull request #413 from math1985/tertiarylinkcolour

Render tertiary_link in correct color
Merge pull request #412 from math1985/primarybridgewidth

Correct widths of bridges and tunnels for primary
Merge branch 'zoom' of https://github.com/math1985/openstreetmap-carto into math1985-zoom
Remove the unnecessary < 14 restrictions.

The symbolizers and properties created at z13 are used at z14 so
don't need to be restricted.
Merge branch 'math1985-zoom'
Merge pull request #408 from math1985/tunnel-group-by

Use layer tag of tunnels for rendering
Merge pull request #409 from math1985/sql-oneway-ssy

Cleanup oneway and railway=spur/siding in SQL
Merge pull request #407 from math1985/track-rendering

Clean up definition tracks