Each board can have a "link" to a source file from an editor (e.g.: PSD)

[audionerd]

Storyboarder should know what source file is linked per board (e.g.: file path to PSD).

• "Open In Editor" will add the PSD path of the created PSD to the JSON file.
• If an artist begins to draw on a linked board, warn first about link being broken.
• • If artist agrees to continue after the warning, remove linkage in JSON. PSD file remains on filesystem until cleanup task is run.
• "Open in Editor" should warn before overwriting an existing PSD.
• "Clean Up Scene" task should not delete PSD files if they are actively linked.
• Clear filesystem watcher on window close

To test:

• Test that thumbnails update (for both currently selected board and not)
• Test closing and re-opening project
• Test closing and re-opening Storyboarder
• Monitor the JSON data and make sure it's changing properly
• Monitor the filesystem and make sure PSDs change as expected
• What happens if Photoshop has a file open, but we've deleted the board?
• Test when .link points to a PSD that does not exist
• What happens if we edit-in-photoshop a board on a different scene? ANSWER: Currently, this will fail silently, unless save happens when scene is open
• Should we stop watching PSDs that aren't part of the new selection? ANSWER: No, for now we'll keep watching until 1) their layer is drawn on/unlinked or 2) the session ends

If a user has a linked PSD open in Photoshop, closes Storyboarder and re-opens, and then re-saves the (still open) PSD, it won't update in Storyboarder. We could begin watching all links when Storyboarder opens a project, but we're not doing that yet. For now, you'll have to notice that it's not updating and choose "Open in Photoshop" again.

Fixes #654

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FUTURE

• We only break the link on pointerdown. Would be better to break the link on any activity that might change the canvas (e.g.: flip, paste)