make speed improvements to py_dict.js

Put doc of builtins in a script builtins_docstrings.js generated by s…

…cript make_builtins_docstrings.py ; remove them from py_builtin_functions.js ; only load builtins_docstrings.js if help() is called on a builtin, or its attribute __doc__ is requested

Update README.md (as suggested by Roger Erens)

Update urllib/parse.py

Change version to 3.0.0rc1

Minor change in console.html

Minor change in console.html

Change adress of devt site from PierreQuentel/brython to brython-dev/…

…brython

Change adress of devt site from PierreQuentel/brython to brython-dev/…

…brython