Dataset management for file sets and PostgreSQL

[saxondigital]

Proposed properties of dataset management:

• DB viewer to navigate datasets within the GUI.
• Each dataset would have its on directory structured similar to existing 'usr' folder.
• Allow for sharing external assets across multiple datasets such as texture maps.
• PostgreSQL DB support for external file path or URL to load textures or other external assets.
• Allow the directory to be compressed into a ZIP file.
• Allow user to choose specific file or the directory to load entire dataset at once.
• Dataset browser to visually choose a dataset represented as a node tree.
• Scene table to hold a list of the assets in the dataset, support imbedding other scene tables.