[whatwg] Canonical Image and Color

[Brian Blakely]

* Proposal

Meta elements for defining a canonical image and color to be associated
with the page(s) in which they are included.  This is intended for use by
user agents and third-party applications (such as social networks),
referred to collectively as "parsers" in this document.  It is inspired by
Microsoft's recent work in site pinning and Apple's "standalone" webapp
implementation in iOS Safari.

* Example

<meta name="image" content="path/to/image.png" />
<meta name="color" content="#123456" />

* Image

Value may be a relative or absolute path to file.  No restrictions on
filetype or resolution.  May also be an animated image or video format.
 Filetypes supported and handling therein is relegated to the parser.

* Color

Value may be any of the CSS named colors, hex codes, RGB, HSL and their
alpha-channel variants.  Once attained by the parser, use is at that
parser's discretion.