* submodule docs are now located at /api/yaml/<name>.html instead of
/api/<name>.html.
* can now simply link to symbols in other modules.
* fixed some links
* fixed quickstart example list
* added quickstart item displaying the new style api
* fixed a bug in presenter that doubled a line in literal/flow style
* added yaml/style that defines representation pragmas
`scalar` and `collection`
* implemented those pragmas
* updated docs. also fixes some invalid links in docs
* Added serialization.txt to doc
* Fixed rendering problem in api.txt
* Use explicit tag when ref type renders to a scalar that can be
parsed to !!null
* Added test cases for this ref type fix