refresh metadata to flathub standards

MANIFEST.in

@@ -1,2 +1,4 @@
 include license.txt COPYING
-include glyphtracer.desktop
+include com.github.jpakkane.glyphtracer.desktop
+include com.github.jpakkane.glyphtracer.metainfo.xml
+include com.github.jpakkane.glyphtracer.svg

com.github.jpakkane.glyphtracer.metainfo.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<component type="desktop">
+  <id>com.github.jpakkane.glyphtracer</id>
+  <launchable type="desktop-id">com.github.jpakkane.glyphtracer.desktop</launchable>
+  <name>Glyphtracer</name>
+  <developer_name>Jussi Pakkanen</developer_name>
+  <summary>Convert images of letters to a font</summary>
+  <metadata_license>CC0-1.0</metadata_license>
+  <project_license>GPL-3.0-or-later</project_license>
+  <url type="homepage">https://github.com/jpakkane/glyphtracer</url>
+  <description>
+    <p>Glyphtracer takes an image that contains pictures of several letters. 
+    It recognizes all them and lets the user tag each letter to a Unicode code point. 
+    It then converts the images to vector form and writes them to a FontForge's data format. 
+    The font can then be finalized with FontForge.</p>
+  </description>
+  <screenshots>
+    <screenshot type="default">
+      <caption>The main Glyphtracer window</caption>
+      <image type="source" width="773" height="609">https://raw.githubusercontent.com/jpakkane/glyphtracer/master/screenshot.jpg</image>
+    </screenshot>
+  </screenshots>
+  <releases>
+    <release version="2.0" date="2021-09-20"/>
+  </releases>
+  <content_rating type="oars-1.1"/>
+  <update_contact>nick_at_nedrichards.com</update_contact>
+</component>