Fix escaped HTML characters bug

With this pull request this svg excerpt : 
```svg
<tspan>&lt;Abri.Co &amp; friends &gt;</tspan>
```
now render the correct unescaped string of text:
>\<Abri.Co & friends \>

instead of:

>\&lt;Abri.Co &amp; friends \&gt;

as Illustrator, Chrome and Safari do.