Create a content explorer window for Unity

[fydar]

Create a content explorer window that can be used to launch content editing windows.

Use the virtual folder structure APIs from #19 to create a hierarchy that is rendered inside Unity using it's TreeView API.

Create a platform for adding more ways of rendering and editing the content of a resource.

Examples include:

• Image files rendered using an image viewer.
• Json, XML and YAML files using syntax-highlighted text.
• EditorSession Json file editing

Tasks

Explorer

• [x] Create a tree view that renders the content of projects
• [ ] Render the content of recently built packages
• [ ] Render project and package dependencies
• [ ] Create a UI for building and summarising projects

Package Editing

• [ ] Create a UI for editing .bproj files
• [ ] Allow for the renaming of resources
• [ ] Allow for the moving of resources
• [ ] Allow for the deletion of resources
• [ ] Allow for the creation of resources
• [ ] Allow for the duplication of resources
• [ ] Allow for the renaming of directories
• [ ] Allow for the moving of directories
• [ ] Allow for the deletion of directories
• [ ] Allow for the creation of directories
• [ ] Allow for the duplication of directories

[fydar]

Work-in-progress screenshot of Json and raw text rendering to the content explorer window.

[fydar]

More work-in-progress gifs.

Now with integration with the node-based behaviour editor.

[fydar]

Previously this editor worked on the notion of "Resources"; however, it's clear to me now that there is rarely a one-to-one correlation of a resource to a file on disk.

It's fine for the editor to interact with resources, however, it should edit on a per-file basis, rather than a per-resource basis.