Emitted when the builder object has been created. It is available as
+.. event:: env-get-outdated (app, env, added, changed, removed)
+ Emitted when the environment determines which source files have changed and
+ should be re-read. *added*, *changed* and *removed* are sets of docnames
+ that the environment has determined. You can return a list of docnames to
+ re-read in addition to these.
.. event:: env-purge-doc (app, env, docname)
Emitted when all traces of a source file should be cleaned from the