[gnome-control-center] (10 commits) Non-fast-forward update to branch wip/gbsneto/list-layout

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

The branch 'wip/gbsneto/list-layout' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  ffcaf43... window: make it a template class
  ffc1066... window: keep searchbar visible when panel changes
  f33316c... window: remove the previous button
  12e1e72... window: keep search button always visible
  3763a15... window: put the search button in the start of the headerbar
  c7daa7a... window: pack the headerbar inside a box
  90a542e... window: introduce the second headerbar
  76f5c41... window: make the sidelist and first headerbar horizontally 

Commits added to the branch:

  30d1459... window: make it a template class
  c9c8dce... window: keep searchbar visible when panel changes
  97537e7... window: remove the previous button
  2d0f815... window: keep search button always visible
  7316c13... window: put the search button in the start of the headerbar
  238d2ca... window: pack the headerbar inside a box
  000cd97... window: introduce the second headerbar
  289d3cb... window: make the sidelist and first headerbar horizontally 
  ccf0369... window: set the default width and height
  d209d86... window: add a nice placeholder view