Move some code around.

Move logs:SignalHandlers to core/crash_reports:CrashReports.
Move all pre-launch windows to core/crash_report_window module.
Move some global code to core/launcher:Launcher.
It should replace settings / platform_specific module in some way.

Telegram/SourceFiles/core/launcher.h

@@ -0,0 +1,45 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop version of Telegram messaging app, see https://telegram.org
+
+Telegram Desktop is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+It is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+In addition, as a special exception, the copyright holders give permission
+to link the code of portions of this program with the OpenSSL library.
+
+Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
+Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
+*/
+#pragma once
+
+namespace Core {
+
+class Launcher {
+public:
+	Launcher(int argc, char *argv[]);
+
+	static std::unique_ptr<Launcher> Create(int argc, char *argv[]);
+
+	int exec();
+
+	QString argumentsString() const;
+
+private:
+	void init();
+	virtual void initHook() = 0;
+
+	int _argc;
+	char **_argv;
+	QStringList _arguments;
+
+};
+
+} // namespace Core