Folder for attribute files etc. shoud match across all applications

Currently QtCreator/SpaceCreator uses ~/local/share/QtProject/QtCreator
Applications like the converter use ~/local/share/ESA/...

Proposed solution would be to replace QStandardPaths by a custom self made version (maybe based on QStandardPaths)

• All should use the same directory (~/local/share/QtProject/QtCreator)
• Add documentation for an overview of which files are used/store/where