bpo-28837: Fix lib2to3 handling of map/zip/filter

[stuarteberg]

The 2to3 tool will automatically wrap calls to map, zip, and filter with list():

# Original:
zip('abc', '123')

# After 2to3:
list(zip('abc', '123'))

...but the tool misses some cases, if the call is followed by a "trailer" such as [0]:

# Skipped by 2to3:
zip('abc', '123')[0]

This PR augments the lib2to3 "fixers" for map, zip, and filter to correctly handle such cases.

http://bugs.python.org/issue28837