OpenCPN 5.10.x locks up with Dutch ENC charts

[mgrouch]

Catalog for Dutch charts:

https://raw.githubusercontent.com/chartcatalogs/catalogs/master/NL_IENC_Catalog.xml

See also:

OpenCPN/OpenCPN#4106

[mgrouch]

As a workaround:

Users are suggested installing and using QtVlm instead of OpenCPN for those charts.