- This commit adapts lxc-clone to be similiar in usage and feel to the other
  lxc-* executables. It builds on the previous extension of the lxc_argument
  struct and now uses the default lxc_arguments_parse() function.
- Options which were not used have been removed.
- The LXC_CLONE_KEEPNAME flag was not respected in the previous version of
  lxc-clone. The culprit is a missing if-condition in lxccontainer.c. As this
  requires a change in one of the API functions in lxccontainer.c it will be
  addressed in a follow-up commit.
Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>