Optional offset for direction-dependent line data

**Is your feature request related to a problem? Please describe.**
The data I'm visualizing has direction-dependent line properties like e.g.

edge_geo,avg_speed_kmph,count
"LINESTRING(9.414 54.8147,9.415 54.8146)",15.2,3
"LINESTRING(9.415 54.8146,9.414 54.8147)",22.2,5

Currently, both lines are rendered above each other, like in the screeshot below.

**Describe the solution you'd like**
I'd like to be able to display the each direction shifted by an offset (or just rendering half of the stroke) according to the line orientation. To accomodate left/right hand drive, a ternary option "no-shift", "shift-right", "shift-left" would be required.

**Describe alternatives you've considered**
Instead of shifting, just rendering the right/left half of a stroke might be easier to realize.

**Additional context**
Screenshot showing lines rendered on top of each other