xObsAsyncImageSource - Asynchronous image source v1.0

Added an installer for Windows to the downloads

- Bumped version to v1.0 since this has been stable and reliable long enough now
- Added text "(Async)" to properties page so that this source can be easily distinguished from the original source

Full Changelog: https://github.com/YorVeX/xObsAsyncImageSource/compare/v0.4...v1.0

Added Linux support

If loading fails the async image source will now keep on trying to load the image every second until it succeeds. This way if the file was locked during the last load attempt (e.g. happens when it is updated at the exact time the image source tries to read the file) it will be updated a second later (whereas the original image source would never recover from this until the image file is updated once more).