AnyImageImporter: detect the *.svg and *.svgz extension.

Not file contents yet because the file can start with a XML preamble,
seven megabytes of comments and only then there's <svg. I'm not in a
mood for that today.

doc/changelog.dox

@@ -996,6 +996,7 @@ See also:
 -   Recognizing 3MF, VRM and USD files in @relativeref{Trade,AnySceneImporter}
 -   Recognizing OpenVDB files in @relativeref{Trade,AnyImageImporter} and
     @relativeref{Trade,AnyImageConverter}
+-   Recognizing SVG file extension in @relativeref{Trade,AnyImageImporter}
 -   @ref Audio::AnyImporter "AnyAudioImporter",
     @relativeref{Trade,AnyImageImporter}, @relativeref{Trade,AnyImageConverter},
     @relativeref{Trade,AnySceneImporter}, @relativeref{Trade,AnySceneConverter}

src/MagnumPlugins/AnyImageImporter/AnyImageImporter.cpp

@@ -141,6 +141,9 @@ void AnyImageImporter::doOpenFile(const Containers::StringView filename) {
             normalizedExtension == ".rgb"_s ||
             normalizedExtension == ".rgba"_s)
         plugin = "SgiImporter"_s;
+    else if(normalizedExtension == ".svg"_s ||
+            normalizedExtension == ".svgz"_s)
+        plugin = "SvgImporter"_s;
     else if(normalizedExtension == ".tif"_s ||
             normalizedExtension == ".tiff"_s)
         plugin = "TiffImporter"_s;

src/MagnumPlugins/AnyImageImporter/AnyImageImporter.h

@@ -94,6 +94,8 @@ Supported formats:
 -   Adobe Photoshop (`*.psd`), loaded with any plugin that provides `PsdImporter`
 -   Silicon Graphics (`*.sgi`, `*.bw`, `*.rgb`, `*.rgba`), loaded with any
     plugin that provides `SgiImporter`
+-   Scalable Vector Graphics (`*.svg`, `*.svgz`), loaded with any plugin that
+    provides `SvgImporter`
 -   Tagged Image File Format (`*.tif`, `*.tiff` or data with corresponding
     signature), loaded with any plugin that provides `TiffImporter`
 -   Truevision TGA (`*.tga`, `*.vda`, `*.icb`, `*.vst` or data with

src/MagnumPlugins/AnyImageImporter/Test/AnyImageImporterTest.cpp

@@ -125,6 +125,8 @@ constexpr struct {
     {"Sillicon Graphics BW", "pixar.bw", false, "SgiImporter"},
     {"Sillicon Graphics RGB", "pixar.rgb", false, "SgiImporter"},
     {"Sillicon Graphics RGBA", "pixar.rgba", false, "SgiImporter"},
+    {"SVG", "lion.svg", false, "SvgImporter"},
+    {"SVGZ", "lion.svgz", false, "SvgImporter"},
     {"TIFF", "image.tiff", false, "TiffImporter"},
     {"TIFF, 3-character extension", "image.tif", false, "TiffImporter"},
     {"TIFF data", "image.tiff", true, "TiffImporter"},