Add partial support for SVG

[qarmin]

Closes #60

This add partial support for SVG.
Most of SVG files which I checked started with <svg

<svg width="40" height="40" viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg">

but some starts with:

<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg t="1604130777424" class="icon"

which makes it impossible to simply search for an SVG file

[johansmitsnl]

Not all svg files start with just <svg. Here a header of a svg:

<?xml version="1.0" encoding="UTF-8"?>
<svg id="Layer_1" xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0 0 850.39 850.39">
  <!-- Generator: Adobe Illustrator 29.2.1, SVG Export Plug-In . SVG Version: 2.1.0 Build 116)  -->
...