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

fortune cookie message = In Träumen und im Leben ist nichts unmöglich.

src/lib/data/storage/sqlite/SqliteStorage.cpp

@@ -1,7 +1,7 @@
 #include "data/storage/sqlite/SqliteStorage.h"
 
 #include "utility/logging/logging.h"
-#include "utility/TimePoint.h"
+#include "utility/TimeStamp.h"
 
 SqliteStorage::SqliteStorage(const FilePath& dbFilePath)
 	: m_dbFilePath(dbFilePath.canonical())
@@ -127,12 +127,12 @@ bool SqliteStorage::isIncompatible() const
 
 void SqliteStorage::setTime()
 {
-	insertOrUpdateMetaValue("timestamp", TimePoint::now().toString());
+	insertOrUpdateMetaValue("timestamp", TimeStamp::now().toString());
 }
 
-TimePoint SqliteStorage::getTime() const
+TimeStamp SqliteStorage::getTime() const
 {
-	return TimePoint(getMetaValue("timestamp"));
+	return TimeStamp(getMetaValue("timestamp"));
 }
 
 void SqliteStorage::setupMetaTable()