Lensfunpy

- Linux 64 bit binary wheels are now provided for easier installation (the same lensfun version as for macOS and Windows wheels is used)
- Fixed handling of string arguments which could have led to random errors (see 6)
- [Documentation](https://letmaik.github.io/lensfunpy/api/) is now hosted on GitHub Pages

- Python 3.6 support
- Dropped Python 3.3. support
- macOS wheels are now only made available for 64bit systems (lensfun depends on glib which became broken as universal binary build, see https://github.com/Homebrew/homebrew-core/issues/5404)
- Fixed bug where accessing `lens.type` (or `print(lens)`) led to an exception for the four fisheye lens subtypes (orthographic, stereographic, equisolid, thoby), see 10