Remove explicit idempotent tests

Issue #57 covered that and made testing for idempotent behaviour
implicit.
Merge pull request #70 from brettcannon/remove_idempotent_redundancy

Remove explicit idempotent tests
Use lib2to3's fix_dict to help with list(dict.items())

Also helps cover dict.viewitems() and friends.

Closes #35
Don't measure coverage for nearly impossible state
Add back in a missing test
Merge pull request #72 from brettcannon/no_cover

Increase test coverage
Merge pull request #71 from brettcannon/fix_dict

Use lib2to3's fix_dict to help with list(dict.items())
Fix wording of copyright notice for fix_input_six.py.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>
Fix wording of copyright notice for fix_metaclass.py.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>
Simplify fix_map

Part of #72
Simplify fix_filter

Part of #72
Simplify fix_zip

Part of #72
Simplify fix_print

Closes #66
Have fix_open subclass fix_file

That guarantees that any open-related scenario is fixed.

Closes #74
Use absolute import

Only skip absolute imports when the only import is a __future__
statement.

Closes #59
Fix reference to 'long'

For all instances of `(int, long)`, change to six.integer_types. For
all other references to `long`, change to `int` through lib2to3.

For #20
Greatly simplify fix_open

Use run ordering to prevent having to subclass.
Bump the priority of fix_import

Guarantees it does its thing before any other fixer accidentally blocks
its execution.
Tweak a comment
Merge pull request #77 from brettcannon/future_import

Use absolute import