Py-appstream

What's Changed
* Stop joining lines, keep translations as they are by PhuNH in https://github.com/PhuNH/py-appstream/pull/2
* Follow appstreamcli convert output format by PhuNH in https://github.com/PhuNH/py-appstream/pull/3
* Support 'extends' tag by PhuNH in https://github.com/PhuNH/py-appstream/pull/4
* Strip whitespaces from every piece of text gotten from XML by PhuNH in https://github.com/PhuNH/py-appstream/pull/5


**Full Changelog**: https://github.com/PhuNH/py-appstream/compare/v0.1.1...v0.1.2

What's Changed
* Fix variable case to stop 'type' from getting into 'Image' serial form by PhuNH in https://github.com/PhuNH/py-appstream/pull/1

New Contributors
* PhuNH made their first contribution in https://github.com/PhuNH/py-appstream/pull/1

**Full Changelog**: https://github.com/PhuNH/py-appstream/compare/v0.1.0...v0.1.1

- Try to be compatible with [`appstreamcli`](https://github.com/ximion/appstream) convert output
- Some attributes are not yet supported
- Parse descriptions more strict: only fully translated languages are accepted
- With tests