Annotations for exports
Write out sorted symbols, excluding inherited ones on private classes

There are cases where a private class may inherit an exportable member (e.g. ol.DebugTile_#getTileCoord comes from ol.Tile#getTileCoord).  We want to avoid making these exportable.
Allow main method to be called from elsewhere
Task for generating a limited set of exports
Use new generate-exports.js task
Regenerate symbols if parents have changed

The generate-symbols.js task runs JSDoc on source files.  Because this takes a long time (13s) to run on the whole library, the resulting symbols file includes additional metadata to make it possible to do incremental symbol generation on subsequent runs.  The 'path' and 'extends' metadata for a symbol are used to determine what needs to be regenerated.
Call generate-symbols.js from build.py
Unused script