Add a arrow symbol (->) to the lexer
Add a arrow symbol (->) to the lexer

Bug #368
Add a test for the arrow operator

Bug #386
Rename test function
When parsing type, expect a single '->' token
Rename byte_types to _byte_types

Bug #331
Only skip Python 2 tests if no Python 2 interpreter
Merge pull request #387 from iankronquist/no-space-in-arrows-368

No space in arrows 368
Merge branch 'rename-byte-types'
Refactor: rename Mapping to MutableMapping
Add A MutableSequence type

MutableSequence includes: list, bytearray, range
Sequence includes: list, tuple, str, bytes, bytearray, range
Add A MutableSequence type for 2.7

MutableSequence includes: list, bytearray, xrange
Sequence includes: list, tuple, str, unicode, bytes, bytearray, xrange
Merge branch 'typing-abcs-396' of github.com:iankronquist/mypy into typing-abcs-396