Bump to v8.12.0

[KaliedaRik]

Release v8.12.0

Breaking changes:

• Phrase entity support for font-variant and font-stretch attributes has been removed. No browser was acting on these attributes when used in font strings, so little/no damage is expected from this change. There is no plan to support these text attributes going forward as their implementation in the 2D Canvas API specs are incompatible with the way Scrawl-canvas works internally.
• Anchor objects (and the new Button objects) now default their focusAction and blurAction attributes to true. These attributes are used to tie keyboard navigation and the canvas display closer together.

New functionality:

• scrawl.importScreenCapture - Similar to the existing scrawl.importMediaStream functionality which makes it easier for users to use media streams (eg: from device cameras) in canvas animations, this new function call will capture a real-time browser tab, window or an entire screen as a video source for use in the animation.
• Scrawl-canvas canvases can now support wide-gamut colors (the display-p3 color space) by adding a data-canvas-color-space="display-p3" attribute to the <canvas> element in HTML code.
• Animation objects can now take a new maxFrameRate attribute to limit the speed at which animations run. This is a necessary change as devices/browsers that run at 120fps become more common.
• A new Scrawl-canvas Button object - this works similarly to existing Anchors, except they trigger some action in response to user action (whereas Anchors trigger a navigation to a new web page).

Improvements:

• Scrawl-canvas now supports defining colors using the CSS color() format, where the browser itself also supports displaying those colors in the <canvas> element.
• Some minor improvements to gradient efficiency.
• New demo test exploring how to use the EyeDropper API (which is only supported by Chrome)
• New demo to test that a Scrawl-canvas canvas behaves appropriately and accessibly when included in HTML markup using the new Popover API (which is not yet supported by Firefox)
• Added a new tabOrder attribute to Anchor (and Button) objects. This allows the tabbing order of these objects to be updated dynamically without affecting the tabbing order of elements in the wider web page beyond the <canvas> element.

Bugfixes:

• We have removed the legacy <nav> div which Scrawl-canvas added at the top of each web page on which it ran.
• We have fixed an annoying tabbing order bug in demo canvas-027 (the interactive video demo).