Roseate needs a way to load images in a separate thread and animate some sort of loading screen at the bottom of the screen to indicate to the user this is occurring.

This is planned to be used in situations where the GUI is already running and we don't want to interrupt the user by freezing the GUI because we are trying to load something in the main thread.

For example with the dynamic scaling feature we will need to be able to request image reloads so we can downsample or upsample the image dynamically as the user zooms in/out of the image. Doing this now would lead to the main thread getting blocked making the GUI seem like it's frozen.

Initial image loads should stay in the main thread unless a config is set by the user to allow it.

This issue will need #20 to be available first.