SVG tref element

[jlpoolen]

Enhancement request: support for the tref element.

https://www.w3.org/TR/SVG/text.html#TRefElement

current attempt generates error message: "There were parsing errors..."

Example:
...<text id="svg_1" fill="red" y="41" x="21.4375">
<tref xlink:href="myserver/test/test_svgedit_tref1.txt"/>
</text>...

where test_svgedit_tref1.txt file has:

<text xml:space="preserve" text-anchor="left" font-family="Courier" font-size="12" id="svg_5" y="54.74456" x="1094.63103" stroke-linecap="null" stroke-linejoin="null" stroke-dasharray="null" stroke-width="0" stroke="#000000" fill="#000000">
<tspan x="10" dy="1em" id="svg_1">TEST</tspan>
</text>

[jlpoolen]

Just to be complete, an attempt to reference tref with and without a <def> causes the same parser error message:
<text id="svg_1" fill="red" y="41" x="21.4375">
<tref xlink:href="#ReferenceText"/>
</text>