Extened docs support: pages and virtual packages

[Deleted user]

• Pages should possible have their own contents in the contents tab (with links to subpages, examples, etc)
• Pages should be able to fold the sidebar, also by default
• Should be able to put pages in packages and add custom packages possibly only with pages and examples
• The intro page should become regular page
• Should have something like {@import <external_markdown_or_example_to_be_imported>}
• Should have something like @def example [id_of_the_example] <language> [description]\n<code>|{@import}
• Should be able to include examples and links to pages in the contents for classes and function, etc. and also in all packages