Refactor lxc-clone
Refactor lxc-clone

- 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 <94aca18939fc64aa4df96ea8cb026da8a2e1541a@gmail.com>

thmo/lxc,hallyn/lxc,ecarrara/lxc,lisongmin/lxc,LynxChaus/lxc,ss1h2a3tw/lxc,rowhit/lxc,QingweiPeterLan/cs188-lxc,caglar10ur/lxc,DarknessBeforeDawn/lxc,ioops/lxc,ecarrara/lxc,fwilson42/lxc,GreatFruitOmsk/lxc,akshaykarle/lxc,yubo/lxc,lisongmin/lxc,Distrotech/lxc,terceiro/lxc,thmo/lxc,yubo/lxc,federicobriata/lxc,yubo/lxc,lisongmin/lxc,fwilson42/lxc,fwilson42/lxc,aeris/lxc,DarknessBeforeDawn/lxc,ysbnim/lxc,tych0/lxc,ksperis/lxc,ioops/lxc,hfuCN/lxc,LynxChaus/lxc,aeris/lxc,JohnPeacockMessageSystems/lxc,QingweiPeterLan/cs188-lxc,akshaykarle/lxc,rowhit/lxc,bmoar/lxc,Ponce/lxc,federicobriata/lxc,thmo/lxc,ioops/lxc,hfuCN/lxc,tych0/lxc,bostjan/lxc,ss1h2a3tw/lxc,caglar10ur/lxc,QingweiPeterLan/cs188-lxc,bostjan/lxc,szaszg/lxc,Ponce/lxc,hfuCN/lxc,ksperis/lxc,raspberrypython/lxc,szaszg/lxc,cjwatson/lxc,raspberrypython/lxc,ysbnim/lxc,terceiro/lxc,hallyn/lxc,bostjan/lxc,terceiro/lxc,szaszg/lxc,ksperis/lxc,ysbnim/lxc,JohnPeacockMessageSystems/lxc,raspberrypython/lxc,LynxChaus/lxc,hallyn/lxc,DarknessBeforeDawn/lxc,akshaykarle/lxc,JohnPeacockMessageSystems/lxc,ecarrara/lxc,cjwatson/lxc,ss1h2a3tw/lxc,bmoar/lxc,armcc/lxc,cjwatson/lxc,Distrotech/lxc,armcc/lxc,GreatFruitOmsk/lxc,federicobriata/lxc,GreatFruitOmsk/lxc,aeris/lxc,tych0/lxc,Ponce/lxc,Distrotech/lxc,bmoar/lxc,caglar10ur/lxc,rowhit/lxc,armcc/lxc