Coordinate libraries maintenance

[leamas]

Is your feature request related to a problem?
We maintain multiple copies of libraries, notably in opencpn-libs and main opencpn/libs causing more work than necessary

Describe the solution you'd like
We should reuse the git submodule opencpn-libs where applicable also in main opencpn.

Describe alternatives you've considered
None.

Additional context
This is certainly for later.
After adding opencpn-libs to main opencpn the actual library copy to use (libs/ or opencpn-libs/) needs to be modified on a case by case basis, possibly after merging the current copies in libs/ and opencpn-libs/)

We need to consider things like the n2kparser which perhaps should be used as a separate submodule rather than as part of opencpn-libs.