Split `definitions/document.ts` into unique files per actor type.
Create `model` folder to store the above types, their factories and the state changing actions.
### Motivation
In order to be more useful as a spritesheet editor, BitMappery now contains a timeline view, a mode where content can be sub grouped into tiles, where each subsequent tile can be traced over the previous one. Each tile can have multiple layers of content for ease of editing.
### Changes
* Introduced Document types `default` and `timeline`
* Introduced LayerRef types (allow grouping Layers)
* Introduced Timeline view for tile based drawing and tracing
* Introduced Document background color (omits need to create background layer for each tile in a timeline)
* Cleaned up some legacy overrides made superfluous by newer dependencies
* Added document presets to document creation flow
### Commits
* Add rel to Layer structure
* Add Document type
* Initial scaffold for timeline view.
* Added initial utility to manage timelines
* Added action to clone all Layers in a tile group
* Moved Layer cloning to layer-util
* Converted zoom tool option panel to TypeScript
* Added action to add a new tile and layer to the Document
* Added action to remove a tile and its layers from the Document
* Added Layer grouping property to Document structure
* Update type check for test
* Initial timeline panel outline
* Created tiles now match Document dimensions
* Added tile cache
* Allow showing a semi transparent carbon copy trace of the previous tile
* Add animation preview window
* Add fps control to animation preview
* Store metadata property inside Documents (allows storing timeline framerate)
* Optimise mobile view for timeline
* Keep thumbnail ratios when previewing tiles and animations
* Button and animation preview window styling
* use RAF-based animation timing in animation preview
* Changes made to layer content now trigger a re-render of the Group tile
* Update Layer reordering logic to also work with subsets
* Optimised animated GIF export, updated pixel art definitions to be more sensible
* Code cleanups
* Added background color to Documents, omitting the need for a background layer on each animation tile
* Removing temp code, updating renderer factory test
* Update layer styling, added tooltip on drag behaviour
* Added document DPI and size unit to meta data
* Refactored deprecated event property from modal key handler
* Remove unused properties from animation preview window
* Update unit test for renderer factory
* Fix bug where closing modals would trigger click on canvas
* Add presets for all Document types
* Added setting to automatically choose appropriate anti-alias setting
* Invalidate tile and thumbnail caches on resize and crop functions. Adjust spritesheet export behaviour
### Motivation
It'd be great if we could see a small thumbnail preview in the layers panel to more easily distinguish between layers visually.
In this changeset we introduce the thumbnail cache. When enabled, each layer is represented by a thumbnail which can be requested from multiple subscribed consumers (currently only the layer panel).
Thumbnail updates are deferred to keep CPU usage low and performance high.
* Restructure and rename actor/renderers
* Rename cache flushing functions to reflect their scope
* Move canvas instance management to dedicated service
* Type resize-canvas-window Vue file
* Create cache for blended layers to speed up rendering on Documents with blended content
* Manage blend mode caching state through layer changes in Document canvas
* Comments updated
* Moving files around
* Omit invisible layers in snapshot rendering
* Add pausing to blend layer cache
* Cleanups and tests for LayerSprite
* Remove logs
* Use actual LayerSprite in test
* Simplify pending check
* Omit flush calls on (un)pausing of cache
* Extend tests for LayerSprite
* Update modifier key tooltip
* Create reusable function for invalidating blend cache
* Updated tests
* Allow partial cache flushes
* Ensure blended layer cache is flushed appropriately on undo
* Pause blend caching while rotating or scaling
* Fix for Safari rendering issues
