ui: load source from directory via MenuBar

Added MenuBar action Project->New, which opens a directory dialog for choosing the new source directory to parse the
files from. The ConfigManager can be created empty now and setValue calls can be used to set values.

fortune cookie message = Your troubles will be faded by the luck you will soon have.

src/lib/Project.cpp

@@ -30,6 +30,16 @@ bool Project::loadProjectSettings(const std::string& projectSettingsFile)
 	return ProjectSettings::getInstance()->load(projectSettingsFile);
 }
 
+void Project::clearProjectSettings()
+{
+	ProjectSettings::getInstance()->clear();
+}
+
+bool Project::setSourceDirectoryPath(const std::string& sourceDirectoryPath)
+{
+	return ProjectSettings::getInstance()->setSourcePath(sourceDirectoryPath);
+}
+
 void Project::parseCode()
 {
 	if (ProjectSettings::getInstance()->getSourcePath() != "")