The go-import-subtree utility is designed to be used with go generate to
import all packages in a sub-folder for side-effect imports.
Using github.com/progrium/go-extpoints
you can have a project with a plugins/ folder, where plugins register
themselves using go-extpoints as a side-effect of being imported.
When combined with go-import-subtree you can import all packages in the
plugins/ folder automatically. Freeing you from maintaining a file importing
all your plugins, just run 'go generate'.