### 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
* Initial implementation to retrieve files from S3 bucket
* Addressed type warnings
* Implemented folder creation and deletion
* Add save UI for S3 bucket storage
* Implemented multipart upload to S3
* Implemented recursive deletion of objects when deleting folders from S3 storage
* Third party storage services can now be initialized from the save window
* Limit max keys for folder request
* Updated docs and integration
* Prevent auto open of file browser when connecting to 3rd party service in save modal
* Use alternate client registration for non-AWS based S3 endpoints
* Addressed issues with local MinIO based storage providers
* Added lazy thumbnail generation to S3 type storage
* Bugfixing
* Uniform click handler
* TDD approach then
* Fixed issue with thumbnail path resolving
* Add retry handler to overcome RequestTimeTooSkewed
* Renamed Selection data structure. Multiple select begins to work
* Saving and loading of multiple selection shapes implemented
* Renamed Document selection properties to avoid confusion
* Renamed and distributed functions between selection and shape utilities
* Fixes to selection toolbox
* Fixed issue with copying across multiple selections
* Final cleanups
* Selection outline is now rendered by interaction pane, not individual layer sprites
* Updated to zCanvas 4.3.1 to fix issue with bounding box detection on rotated content
* Refactored rectangles to always use left and top
* Layer scaling, rotating and mirroring is now a fast, synchronous operation
* Snapshots are now always of rendered layer content
