Handling of Text Areas and Graphical Elements

Currently, all Text Areas from all formats are converted to the internal type "Pathway", which is cumbersome, prevents efficient use of Text Areas and Graphical Elements (e.g. see #1322 (closed) as a related issue).

This could be addressed by handling (or creating on import) specific layers containing only Text Areas or Graphical Elements, which will not be converted to the type "Pathway".