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.
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 github.com:bnmnetp/skulpt
Merge branch 'master' of github.com:rixner/skulpt into rixner-master
Clean up type-checking in builtin functions to match Python.
Add missing nb$add and nb$inplace_add methods to list, tuple, and string objects.
Call nb$add methods of sequence types when using a + operator.
Make sum handle non-number objects and throw errors like Python.
Add missing nb$multiply and nb$inplace_multiply methods to list, tuple, and string objects.
Call nb$multiply methods of sequence types when using a * operator.
Test case to check user-defined operator overloading methods.
Fix builtin pow function to properly handle nmber and lng objects.
Avoid spurious failures of t422.py.  Could it really be that different coprocessors will occasionally cause this test to fail even on the same machine?
Modify the urllib from web cat's branch so that it works with a simple synchronous xmlhttprequest object.
Merge branch 'master' of github.com:rixner/skulpt into rixner-master
Add an external configuration variable Sk.inputfun.  This can be configured similar to the Sk.read variable for importing files.  It is backward compatible with the current practice of using prompt.