1. Apps that don't have "standard" versioning formats now automatically stop using version detection. This will prevent users from having to learn about this feature and enable it manually.
- For such Apps, the "standard" version detection option is greyed out.
2. The Mullvad Source recently broke due to a slight change in their website design. This is now fixed.
- Mullvad also now provides an in-app changelog via their official GitHub repo.
3. Code has been refactored for readability (specifically the version detection code and UI code for most screens).
4. Minor UI tweaks and bugfixes.
- All Sources now have a "Track-Only" option that will prevent Obtainium from looking for APKs (though the App must still have a release of some kind so that a version string can be grabbed).
- These Apps cannot be installed through Obtainium, but update notifications will still be sent.
- The user needs to manually mark them as updated when appropriate.
- This addresses issue #119.
- It also partially addresses #44 by allowing some sources to be configured as "Track-Only"-only. The first such source (APKMirror) will be added later.
- Includes various UI changes to accommodate the above change.
- Also makes App loading a bit more responsive (sending Obtainium to the background then returning will now cause App re-load to pick up changes in App versioning that may have been made in the meantime, for instance through update checking).
