coastline: check for correct orientation

For simple closed ways: Winding order should follow "right hand rule" (i.e. land is on the left side of the direction of the way)

For non-closed ways: The direction of the way should be the same as any adjacent coastline ways.¹

From the wiki:

The direction the ways are drawn is very important! They must be drawn so that the land is on the left side and water on the right side of the way (when viewing in the direction of the way arrows). If you regard this as tracing around an area of land, e.g., an island, then the coastline way should be running counterclockwise.

Footnotes

1. This can only be checked for if any adjacent coastline ways are loaded which might not always be the case. ↩