Ufolib

- ufoLib now requires the `fs` module, also know as `pyfilesystem2`. It will be installed automatically when installing ufoLib via `pip`.
https://pypi.org/project/fs/
https://github.com/PyFilesystem/pyfilesystem2
- Added support for reading and writing UFOZ, an alternative zip-compressed UFO file format.
- Moved test suite outside of the ufoLib package, in an external 'tests' folder.
- Removed deprecated function `convertUFOFormatVersion1ToFormatVersion2`.
- Changed license to MIT License.

**NOTE**: Except for bug fixes, v3.0 will be the last release for ufoLib as a standalone package. From now on, development will continue over at the https://github.com/fonttools/fonttools project.

- Read features.fea as UTF-8 encoded text file.
- Fix issue when writing non-ASCII characters in a glyph's note text (googlei18n/fontmake467).

Fixed issue whereby python2 `str` (same as `bytes`) objects were written as property list's `<data>` elements instead of `<string>` elements.

Added `use_builtin_types` option to `plistlib.load/dump` to control whether `<data>` elements should be loaded as built-in `bytes` (this is the default when running ufoLib under python3), or whether they should be wrapped in a `plistlib.Data` object (default when running ufoLib under python2); when used with the `dump` function, this option controls whether `bytes` values should be written as `<data>` (python3) or as `<string>` (python2) elements.

https://github.com/unified-font-object/ufoLib/issues/162
https://github.com/unified-font-object/ufoLib/pull/163
https://github.com/unified-font-object/ufoLib/issues/164

- The `lxml` and `singledispatch` requirements are now optional. When not present, the built-in `xml.etree.ElementTree` library is used. To install ufoLib with lxml support you can do like this: `pip install ufoLib[lxml]`.
- Added new `ufoLib.plistlib` implementation that works the same way on both python 2 and python 3, and matches the python3's `plistlib` API (160).
- Added new `ufoLib.etree` module that exports the same ElementTree interface using either `lxml` or `xml.etree` (built-in) as backends, depending on the availability of former (161).
- glifLib: use double quotes in XML declaration like previous ufoLib versions (159).
- Set up test coverage and upload coverage report to codecov.io.

Fixed issue when parsing GLIF xml from a Unicode string containing an explicit XML encoding declaration. The latter is ignored and UTF-8 encoding is always assumed (157).

- Fixed issue introduced in v2.2 whereby the XML declaration was not written at the top of GLIF files and in the string returned from `writeGlyphToString` function (157).