v0.0.3-alpha4

Full Changelog: v0.0.2...v0.0.3-alpha4

New features:

1. Line endings feature finally works, #18
2. File previews for images (XPM and SVG), markdown, json and XML, #21
3. Application test for updates, and added also testing channel support, #27
4. When you put your cursor over a word, it will get selected over all the document, diegoiast/qutepart-cpp#5
5. Minor fixes, #2,
6. ּSide panels state is saved between runs, diegoiast/qmdilib#4
7. Speed up in startup, due to lazy loading documents, #17