logic: Added update checker connecting to online API

* connects to https://www.sourcetrail.com/api/v1/versions/latest
* sends information about OS, platform, license type, current version and a unique user token
* Automatic update check is enabled via Startscreen and performed once every 24 hours on window focus
* Update check can be forced by clicking on "check for new version" on start screen
* renamed TimePoint to TimeStamp

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src/lib_gui/qt/element/QtCodeFileTitleButton.h

@@ -4,7 +4,7 @@
 #include <QPushButton>
 
 #include "utility/file/FilePath.h"
-#include "utility/TimePoint.h"
+#include "utility/TimeStamp.h"
 
 class QtCodeFileTitleButton
 	: public QPushButton
@@ -16,7 +16,7 @@ public:
 	virtual ~QtCodeFileTitleButton();
 
 	void setFilePath(const FilePath& filePath);
-	void setModificationTime(const TimePoint modificationTime);
+	void setModificationTime(const TimeStamp modificationTime);
 	void setIsComplete(bool isComplete);
 	void setProject(const std::string& name);
 
@@ -30,7 +30,7 @@ private slots:
 
 private:
 	FilePath m_filePath;
-	TimePoint m_modificationTime;
+	TimeStamp m_modificationTime;
 	bool m_isComplete;
 };