ui: reworked StartScreen and ProjectSettupScreen UI flow

* realigned buttons and elements
* fixed retina styles for mac
* removed MessageLoadSource and subsequent functionality
* edit existing project through menu
* browsing paths from the line item in QtDirectoryListBox
* grow QtDirectoryListBox instead of scroll
* take any file or directory as valid path
* fixed new project setup screen background
* fixed screen handling on cancelation

src/lib/settings/Settings.cpp

@@ -57,16 +57,16 @@ void Settings::clear()
 	m_filePath = FilePath();
 }
 
-Settings::Settings()
-{
-	clear();
-}
-
 const FilePath& Settings::getFilePath() const
 {
 	return m_filePath;
 }
 
+Settings::Settings()
+{
+	clear();
+}
+
 void Settings::setFilePath(const FilePath& filePath)
 {
 	m_filePath = filePath;