support cycleway:left/cycleway:right in map style or discourage it in validator

[mkoniecz]

What steps will reproduce the problem?

1. encounter contraflow tagged by an iD user (cycleway:left=opposite tags) -like ​https://www.openstreetmap.org/way/26037139

What is the expected result?

It is rendered (like or similar to cycleway=opposite) or validator proposes an automatic fix to cycleway=opposite

What happens instead?

It is not rendered, validator is not complaining

Please provide any additional information below. Attach a screenshot if possible.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-11-07 22:38:38 +0100 (Wed, 07 Nov 2018)
Build-Date:2018-11-08 02:34:19
Revision:14418
Relative:URL: ^/trunk

Identification: JOSM/1.5 (14418 en) Linux Ubuntu 16.04.5 LTS
Memory Usage: 685 MB / 869 MB (239 MB allocated, but free)
Java version: 1.8.0_191-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (34535)
+ buildings_tools (34572)
+ continuosDownload (82)
+ imagery_offset_db (34641)
+ measurement (34529)
+ reverter (34552)
+ todo (30306)

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.

[mkoniecz]

Note: it may be also cycleway:right=opposite in countries with driving side on the left or with oneway=-1 tagging.

Note2: I encountered some people believing that cycleway=opposite should be not used and that oneway:bicycle=no is sufficient in cases where no lane is painted (that would be cycleway*=opposite_lane).