util: fix strict aliasing violations in use of struct inotify_event v5

There is alot of cleanup that will have to happen to turn on
-fstrict-aliasing, but I think our code should be "correct" to the rule.
sd-bus: rename sd_bus_open_system_container() to sd_bus_open_system_machine()

Pretty much everywhere else we use the generic term "machine" when
referring to containers in API, so let's do though in sd-bus too. In
particular, since the concept of a "container" exists in sd-bus too, but
as part of the marshalling system.
util: make creation time xattr logic more generic
machined: fix writability check for GPT images
import: make the dkr import URL a part of the import object, not the import name object
import: remember when we were finished importing
import: print friendly error messages on errors
import: three minor fixes
import: add a new "pull-gpt" verb for downloading GPT disk images from the internet
update TODO
update TODO