ui: added help texts to directory list boxes

* added a ? button to the labels of the directory list boxes to show help messages
* added a window stack to QtMainWindow for easier screen handling
* added a button to the preferences in the project setup
* removed 'has seen settings' flag from AppSettings

src/lib/settings/ApplicationSettings.cpp

@@ -131,16 +131,6 @@ bool ApplicationSettings::setRecentProjects(const std::vector<FilePath> &recentP
 	return setPathValues("user/recent_projects/recent_project", recentProjects);
 }
 
-bool ApplicationSettings::getUserHasSeenSettings() const
-{
-	return getValue<bool>("user/has_seen_settings", false);
-}
-
-void ApplicationSettings::setUserHasSeenSettings(bool hasSeenSettings)
-{
-	setValue<bool>("user/has_seen_settings", hasSeenSettings);
-}
-
 int ApplicationSettings::getPluginPort() const
 {
 	return getValue<int>("network/plugin_port", 6666);

src/lib/settings/ApplicationSettings.h

@@ -49,9 +49,6 @@ public:
 	void setCodeSnippetExpandRange(int range);
 
 	// user
-	bool getUserHasSeenSettings() const;
-	void setUserHasSeenSettings(bool hasSeenSettings);
-
 	std::vector<FilePath> getRecentProjects() const;
 	bool setRecentProjects(const std::vector<FilePath>& recentProjects);