Port Connectivity and Straits

[docuracy]

The current COASTAL_SEA_RESOLUTION = 7 is too low for connectivity through straits and harbour mouths. Regenerate with resolution 8: the previous constraint on graph size has been removed by splitting nodes and edges into 1MB chunks.

After regeneration, remove any nodes and edges which are disconnected from the main graph network.

These may be single nodes, as in the case of Christchurch (UK):

Or disjointed nodes and edges, as at Plymouth (UK):

Calais (FR) is disconnected because of its modern harbour wall:

Istanbul (TR) and the Black Sea are disconnected due to narrow straits: