[gnome-control-center] (13 commits) ...Introduce interactive test for panels

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

Summary of changes:

  81fa6f1... build: Alphabetically sort source files (*)
  a6c983d... panel-loader: Use #pragma once (*)
  9d88b84... panel-loader: Assert get_type() function (*)
  6a50a21... panel-loader: Define vtable struct in the header (*)
  d1fe090... panel-loader: Rename all_panels to default_panels (*)
  31a5d55... panel-loader: Reorder functions (*)
  867a35d... panel-loader: Simplify listing panels (*)
  62d3fb9... panel-loader: Allow overriding panel vtable (*)
  19bd9b8... build: Add more files to libshelltest (*)
  9a2c5dc... panel-loader: Document public functions (*)
  14583e9... build: Reorganize shell libraries and dependencies (*)
  c4c901f... panel-list: Dynamically show Details/Devices row (*)
  65ede4f... Introduce interactive test for panels (*)

(*) This commit already existed in another branch; no separate mail sent