Add special rendering for shop=optician

[kocio-pl]

We should start rendering shop=optician, probably with this icon from osmfr-cartocss fork:

https://github.com/cquest/osmfr-cartocss/blob/master/symbols/optician.svg

[It was proposed in meta-issue #1402]

[matkoniecz]

shop=optician is already rendered, with generic shop icon (a purple dot). Is it intended as "render shop=optician with a special icon?" For list of rendered tag you may consult https://github.com/matkoniecz/CartoCSSHelper/blob/master/style_specific/default_osm_style.rb or search in code - https://github.com/gravitystorm/openstreetmap-carto/search?utf8=%E2%9C%93&q=optician

[matkoniecz]

The same applies to other clones of this ticket.

[kocio-pl]

I thought that is clearly written in the body of the issue - but of course I can also make title more clear too.

[nebulon42]

optician-18.svg:

[kocio-pl]

Good and recognizable.

[nebulon42]

Apparently closing with the commit in #1493 did not work. Should be closed.