Add text label rendering for natural=bay mapped as linear way

[jeisenbe]

Changes proposed in this pull request:

• Render name labels for natural=bay mapped as linear ways, using same style as natural=strait

Explanation

• Currently we render name labels for natural=bay mapped as an area or as a node. However, there are almost 400 bays mapped as linear ways, especially in areas with fjords such as Norway, Greenland and Chile. Many of these bays are long, narrow and curving, so it is reasonable that some mappers like to map these as linear ways.
• Recently we added rendering for straits mapped as linear ways in PR Add rendering for straits mapped as linear ways #3733 - this new PR will complete the rendering for bays as well, using the same style as that used for straits in the former PR
• 99% of the bays mapped as ways could be rendered as early as z13, but the initial zoom level is set at z14 to be consistent with the current rendering of bay nodes.

Test rendering with links to the example places:

Chile: https://www.openstreetmap.org/#map=14/-42.2631/-72.4470
Before z14

After z14

After z15

Norway: https://www.openstreetmap.org/#map=14/59.0483/5.6642
Before z14 - straits render (mapped as linear ways), but not the bay

After

[matkoniecz]

Sorry for a long time without review. For now I created https://josm.openstreetmap.de/ticket/17727#ticket (JOSM validator complaint is not a blocker, but maybe there will be some useful comment there)

EDIT: fixed, with some other false positives as a bonus in https://josm.openstreetmap.de/ticket/17727#comment:2

#!CommitTicketReference repository="josm" revision="15081"
fix #17727
- allow lines for natural=bay
- add bay=fjord checkbox in natural=bay preset
- don't warn about long way segments of bay=fjord ways

I opened also openstreetmap/iD#6379

[matkoniecz]

Thanks, and again sorry for a long wait.

BTW, iD and JOSM now accept linear natural=bay though it may require updating to version more recent than released to a general public.