ui: added info screen for indexer crash investigation

* in case Coati crashes while indexing this screen will inform the user of further steps to take in order to find out what happened

src/lib/ApplicationStateMonitor.cpp

@@ -0,0 +1,58 @@
+#include "ApplicationStateMonitor.h"
+
+#include "settings/ApplicationSettings.h"
+
+std::shared_ptr<ApplicationStateMonitor> ApplicationStateMonitor::getInstance()
+{
+	if (!s_instance)
+	{
+		s_instance = std::shared_ptr<ApplicationStateMonitor>(new ApplicationStateMonitor());
+	}
+	return s_instance;
+}
+
+std::vector<FilePath> ApplicationStateMonitor::getStoredIndexingFiles()
+{
+	return ApplicationSettings::getInstance()->getIndexingFilePaths();
+}
+
+void ApplicationStateMonitor::clearStoredIndexingFiles()
+{
+	ApplicationSettings::getInstance()->setIndexingFilePaths(std::vector<FilePath>());
+	ApplicationSettings::getInstance()->save();
+}
+
+void ApplicationStateMonitor::clearIndexingFiles()
+{
+	std::lock_guard<std::mutex> lock(m_indexingFilesMutex);
+	m_indexingFiles.clear();
+	storeCurrentState();
+}
+
+void ApplicationStateMonitor::addIndexingFile(FilePath file)
+{
+	std::lock_guard<std::mutex> lock(m_indexingFilesMutex);
+	m_indexingFiles.insert(file);
+	storeCurrentState();
+}
+
+void ApplicationStateMonitor::removeIndexingFile(FilePath file)
+{
+	std::lock_guard<std::mutex> lock(m_indexingFilesMutex);
+	m_indexingFiles.erase(file);
+	storeCurrentState();
+}
+
+std::shared_ptr<ApplicationStateMonitor> ApplicationStateMonitor::s_instance;
+
+ApplicationStateMonitor::ApplicationStateMonitor()
+{
+}
+
+void ApplicationStateMonitor::storeCurrentState()
+{
+	std::vector<FilePath> indexingFiles;
+	indexingFiles.insert(indexingFiles.begin(), m_indexingFiles.begin(), m_indexingFiles.end());
+	ApplicationSettings::getInstance()->setIndexingFilePaths(indexingFiles);
+	ApplicationSettings::getInstance()->save();
+}