Add new category "color_coded" for rendering of trails

For the purpose of rendering the color-coded trails using the tag "colour" or "color" (when tags "osmc_symbol" are not used)

See: https://groups.google.com/forum/#!topic/osmand/eLQiAMXYxu0

Link to a map with an explanatory view routes rendered in color: http://osmapa.pl/?lon=16.31899&lat=54.18042&zoom=13&map=1&o=TTFF

See also the example of tagging in my country: http://cycling.waymarkedtrails.org/en/relation/111432?zoom=13&lat=54.22628&lon=16.40435&hill=0#pref