Deprecate glyphRef, glyph, and tref

[AlienKevin]

I noticed that glyphRef, glyph, and trefhave been deprecated lately accordingly to MDN.

Browser compatability:

• glyph
• glyphRef
• tref

[rupertlssmith]

You initially mentioned SVG 2.0. Last time I looked into this (a while back), I got the impression that 2.0 is stalled, and browsers tend to support 1.1 (more or less). Are things starting to move again on 2.0?

I wondering what is the best way to proceed?

1. Remove these functions.
2. Add a comment to their docs to say they are deprecated.

Also worth considering, this package could be used to produce SVG for things other than browsers. For example, I have used it to output SVG that I then loaded into Inkscape. Browsers is the primary target though.

[AlienKevin]

I think SVG 2.0 is indeed rolling out very slowly. I think your option (2) would be the best currently. We can say that the function is deprecated in 2.0 and possibly point out new alternatives.

[AlienKevin]

@rupertlssmith On a side note, go ahead if you want to make a release. This whole SVG 2.0 thing is progressing very slowly.