GUI: Add missing flags + rework

Added missing flags
Resized to keep a coherent look
Replaced complex flags with simpler versions

default/icons/flags/da.svg

@@ -1 +1,45 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 37 28"><path fill="#c60c30" d="M0 0h37v28H0z"/><path fill="#fff" d="M0 12h12V0h4v12h21v4H16v12h-4V16H0z"/></svg>
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   viewBox="0 0 900 600"
+   version="1.1"
+   id="svg6"
+   sodipodi:docname="da.svg"
+   width="900"
+   height="600"
+   inkscape:version="1.1.1 (3bf5ae0d25, 2021-09-20)"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <defs
+     id="defs10" />
+  <sodipodi:namedview
+     id="namedview8"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="0"
+     showgrid="false"
+     inkscape:snap-page="true"
+     inkscape:zoom="0.1767767"
+     inkscape:cx="-8.4852814"
+     inkscape:cy="-472.34733"
+     inkscape:window-width="1920"
+     inkscape:window-height="1017"
+     inkscape:window-x="-8"
+     inkscape:window-y="-8"
+     inkscape:window-maximized="1"
+     inkscape:current-layer="svg6" />
+  <path
+     fill="#c60c30"
+     d="M 0,0 H 900 V 600 H 0 Z"
+     id="path2"
+     style="stroke-width:22.8306" />
+  <path
+     fill="#ffffff"
+     d="M 0,257.14286 H 291.8919 V 0 h 97.29729 V 257.14286 H 900 v 85.71428 H 389.18919 V 600 H 291.8919 V 342.85714 H 0 Z"
+     id="path4"
+     style="stroke-width:22.8306" />
+</svg>