overridden methods get docstrings copied

Fix issue #540: methods that are overridden only have the first definition get the docstring. This branch adds a script that copies it over to subsequent definitions.

As a follow-up, we should probably add a directory for random snippets of code like `synchronousRequire.js`, `license_header.txt`, `jsdoc_copy.py`, and maybe some json files that don't seem helpful.