backport PR10267 https://github.com/bitcoin/bitcoin/pull/10267/files
25b7ab9 doc: Add release notes for -includeconf (Karl-Johan Alm)
0f0badd test: Test includeconf parameter. (Karl-Johan Alm)
629ff8c -includeconf=<path> support in config handler, for including external configuration files (Karl-Johan Alm)
Pull request description:
Fixes: #10071. Done: - adds `-includeconf=<path>`, where `<path>` is relative to `datadir` or to the path of the file being read, if in a file - protects against circular includes - updates help docs ~~~Thoughts:~~~ - ~~~I am not sure how to test this in a neat manner. Feedback on this would be nice. Will dig/think though.~~~
Tree-SHA512: cb31f1b2f69fbc0890d264948eb2e501ac05cf12f5e06a5942f9c1539eb15ea8dc3cae817f4073aecb2fcc21d0386747f14f89d990772003a76e2a6d25642553