Give oceans outline and simplify shapefiles on z0-7

[matthijsmelissen]

Before:

After:

Still needs testing on more realistic data.

[kocio-pl]

Looks nice for me.

[rrzefox]

deployed in the usual location for global testing. Looks good IMHO in the low zoom levels. Looks a bit weird on Z7 where it overlaps with dashed borders, e.g. http://bl.ocks.org/matthijsmelissen/raw/af7a602c222dbf1ff1a2c0d84ed755b7/#7.00/37.519/16.197

[matthijsmelissen]

I reduced the simplification to prevent artefacts at the antemeridian (visible in the demo above).

Rendering demo:

As far as I'm concerned this is ready to be merged.

[matthijsmelissen]

@kocio-pl What do you think?

[kocio-pl]

I still like it 😄 however I'd like to know if it won't produce performance problems (see also #3103 (comment))? Do you have the idea how should we estimate it in general?

[matthijsmelissen]

I don't expect performance problems. The problems in #1938 where caused by the ST_Within check (we were checking for admin polygons located within big admin_level 2 polygons), which we don't do now - this is a totally different approach.

It seems to run without problems on @rrzefox's server.

[pnorman]

👍 based on previews, but I haven't run it myself.

[kocio-pl]

I think this is a small side effect of this change - when the river mouth is big you can see this outline on the water up to z7: