function linkAll () {
	return this
		::mergeMap((dep) => [getDirectLink(dep), ...getBinLinks(dep)])
		::map(([src, dst]) => resolveSymlink(src, dst))
		::mergeMap(([src, dst]) => {
			log(`symlinking ${src} -> ${dst}`)
			return util.forceSymlink(src, dst)
		})
}
symlink the intermediate results of the underlying observable sequence
@return {Observable} - empty observable sequence that will be completed
once all dependencies have been symlinked.