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.
Now you can type "endpoints" in Settings and choose a file with
a complete set of dc_options that will be used instead of built-in
or received through mtproto config till the end of current session.
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 base::lambda can be copied and can wrap any immutable lambda.
For mutable lambdas there is base::lambda_once (which you're
supposed to call only once to pass data through lambda captures,
for example by using std::unique_ptr). Generally base::lambda is
passed by value and base::lambda_once is passed by rvalue reference.
Left: auto update, privacy and security, local storage box +
some minor things, like design fixes, codes like loadlang and
clearing of the local storage (box) and temp download folder.
Now the background of boxes is separated to another widget.
This will allow to use a special layer widget (like settings)
together with the usual layers-boxes upon it, moving the special
widget behind the dark background when a usual layer-box is shown.
