PlatformIO is great. If you want to do serious work, and not just mess around with Arduino, it provides a great ecosystem and excellent tooling. No custom IDE necessary.
It is! :)
http://docs.platformio.org/en/latest/librarymanager/index.ht...
Please note that you can manually update manifest and make PR to author's repository. Click on "Manifest" tab when looking at a library in Web Registry and you will see "Edit" button.
I'll provide the counterpoint. If I want to do serious work, then PlatformIO is too constraining, and doesn't offer a painless way out of these constraints. Other than not to use it.