apptools version 4.5.0

Changes

• Add missing long_description_content_type field in setup. (#108)
• Remove use of 2to3. (#90)
• Use etstool for CI tasks. Setup travis macos and appveyor CI. (#92)
• Temporarily change cwd when running tests. (#104)
• Update broken imports. (#95)
• Add six to requirements. (#101)
• Remove one more use of the deprecated set method. (#103)
• Use trait_set instead of the now deprecated set method. (#82)
• Address one more numpy deprecation warning. (#100)
• Address numpy deprecation warnings. (#83)
• Test the package on Python 3.5, 3.6 on CI. (#78)
• Fix mismatched pyface and traitsui requirements. (#73)
• Drop support for Python 2.6. (#63)
• Fix state_pickler.dump on Python 2. (#61)
• Fix a few spelling mistakes in documentation. (#87)