Bump to v8.15.0

[KaliedaRik]

Breaking changes:

• Fixing the scaled positioning bug affecting Oval, Rectangle and Tetragon entitys means that these entitys now act correctly when scaled. Canvas scenes previously created with workarounds for the issue will need to be updated
• Tighten up the checks around which DOM elements can become SC Stacks, and which ones can become SC Elements. This may break existing Stack-based projects.
• Deprecate and remove the stack.apply, canvas.apply and element.apply functions, replacing them with new stack.reset and canvas.reset functions.

New functionality:

• Artefact group attribute will now accept a Cell object as a value
• New Loom attribute sourceExpansionFactor to help solve poor display of distorted images
• Added functionality to allow the scaling of entity shadows (similar to scaling line widths), controled by a new flag attribute scaleShadow
• Added a new splitShift function to allow for the movement of Cell edge strips from one side of the Cell to the other. Should help to make it easier to build animated tiling and infinite scroll scenes
• New Cell functions - getCellData, paintCellData - that supply the user with a capture of the Cell engine's imageData, alongside a new pixelState object which gives each pixel some state

Improvements:

• Security - updated dev dependency packages to latest version
• Documentation - started writing some higher level overview docs of the library's philosophy and its code base's practicalities (early work-in-progress)
• Typescript annotations in the test demo files
• Cleaned up factory/group.js file, removing unused code
• Improvements (and a minor bugfix) to the blur and gaussianblur filters - which now have their own Demo tests.
• Cleared out the DOM-related CSS checks for Stack, Canvas and Element artefacts - there's no need for this sort of functionality in SC now. Instead we introduce a short list of CSS properties which dev-users cannot update using SC set({ css: {key: value} }) functionality.
• Updated test demo DOM-003 to share a better example of how to wrap SVG elements into an SC Stack.
• Ripped out all code relating to the CSS smoothFont property - which is not part of the Web standards.
• Updated the Element kill function to accept a boolean argument which, when set to false, will not remove the associated DOM element from the document.
• Removed redundant code, relating to cloning functions, from SC clone functionality across the repo.

Bugfixes:

• Small Vector bug fixed
• Fixed issue where entity GCO and filters were interfering with each other, preventing the display of entitys on non-base Cells
• Fixed a scaled positioning issue for Oval, Rectangle and Tetragon entitys
• Fixed a dynamic radius positioning issue for Star and Cog entitys
• The gaussianblur filter was spreading beyond its entity's shape. This has been fixed in a non-breaking way so the errant functionality remains the default.
• Unnecessary mixins were being added to mixin/dom.js - these have been moved to factory/canvas.js where they are needed. Bug was not breaking functionality in any way.
• Fixed the (long neglected) Element stampOrder bug.

New test demo screenshots

Canvas-060 - Wheel entity attributes and functionality

Canvas-062 - Tetragon and Oval entity attributes and functionality

Canvas-063 - Rectangle entity attributes and functionality

Canvas-064 - Polygon entity attributes and functionality

Canvas-065 - Star entity attributes and functionality

Canvas-066 - Spiral entity attributes and functionality

Canvas-067 - Cog entity attributes and functionality

Canvas-069 - Test Cell splitShift functionality (shift only)

Canvas-070 - Test Cell splitShift functionality (infinite scroll)

Canvas-071 - Using getCellData, paintCellData functionality

Canvas-072 - Public transport furniture cover design

Particles-017 - Dynamic update of particle colors

Filters-033 - Parameters for: blur filter

Filters-034 - Parameters for: gaussianblur filter