* Migrate to `unittest2`
why:
Global symbol overflow when running NIM 1.2 on Github ci suggests that
unit tests run sort of separately. The replacement library `unittest2`
provides that.
* Build ci dependencies
* Initial commit of UserOnly Windows ACL settings for files and folders.
* Move ACL procedures to windows/acl.
Move ACL tests to test_winacl.nim.
* Add test_winacl.nim
* Fix *nix compilation problem.
* More proper fix for *nix targets.