A first cut at Python's urllib.request module. Basically only supports urlopen right now, but it's enough for students to get data from web services.
Make compiler use Sk.builtin.none object instead of null for 'None' in Python.
Make compiler use Sk.builtin.bool instead of Javascript booleans for Python values.
Clean up richCompareBool and get rid of unnecessary code.
Made self not optional is list_sort_ function
Small changes to lib modules to make compatible with Sk.builtin.none.
Merge pull request #102 from albertjan/little-bug

Made self not optional in list_sort_ function
Merge branch 'master' of https://github.com/bnmnetp/skulpt
Merge branch 'master' of https://github.com/david-geo-holmes/skulpt
Merge branch 'master' of github.com:bnmnetp/skulpt
Merge branch 'master' of github.com:rixner/skulpt into rixner-master
Merge branch 'master' of https://github.com/bnmnetp/skulpt
Merge Skulpt changes for None/True/False Python types.