This will at least make it a bit better in #3598.
The real solution with remembering custom backgrounds for both
night mode on and off doesn't fit with current theming way too well.
Also allow server-side search inside restricted users list.
Also allow server-side search inside kicked users list.
Also allow PeerListController to work not only in PeerListBox.
Extend the window size after the tabbedSelectorSectionEnabled flag
is already set to true. Otherwise we extend the window and switch
to a normal from single column layout before showing the sidebar.
A lot of people didn't know how to bring the dialogs column back
after it was gone in a wide single column MainWindow.
Now we switch to a two column layout if the window allows it,
preserving the emoji / stickers / GIFs section in case it is shown.
Also implement panels that appear in all spaces on macOS.
Using them for calls panels and custom notifications, so it
will be possible to use custom notifications in macOS as well.
GIFs get paused if some other layer is displayed above.
Media preview > Box or layer > Saved GIFs panel > Inline bot results.
If any of those is displayed, GIFs inside message history pause too.
Currently the build without implicitly included precompiled header
is not supported anyway (because Qt MOC source files do not include
stdafx.h, they include plain headers).
So when we decide to support building without implicitly included
precompiled headers we'll have to fix all the headers anyway.
Some major platform-dependent file operations refactoring.
All methods like "open file", "open file with", "show in folder"
were moved to core/file_utilities module with platform-dependent
backends. All methods interacting with DesktopServices made async.
Now each platform-dependent module declares its interface in
platform/platform_module.h file and after that includes platform-
specific headers like platform/win/module_win.h with implementation.
Also removed the legacy WinRT platform-dependent implementations.
