Don’t separate combining characters in SVG text

[liZe]

SVG allows glyphes to be positioned separately. Because of this, we have to draw text glyph by glyph.

Unfortunately, that’s not what we do: we draw codepoint by codepoint. It obviously gives broken results for combining characters, ligatures, etc.

A dirty workaround would be to draw the whole text instead of separating codepoints when there’s no specified x, y, dx, dy or rotate values for specific glyphes (which is the most common case by far).

SVG is not really clear about the way combining characters have to be handled, but SVG2 gives a detailed explanation: https://svgwg.org/svg2-draft/text.html#TSpanNotes

(Of course, rtl and bidi are not supported yet in this case. Let’s keep that problem for a future issue.)