use DrawableVector for middle square marker

xwords4/android/app/src/main/java/org/eehouse/android/xw4/BoardCanvas.java

@@ -164,7 +164,7 @@ public class BoardCanvas extends Canvas implements DrawCtx {
         m_strokePaint = new Paint();
         m_strokePaint.setStyle( Paint.Style.STROKE );
 
-        m_origin = res.getDrawable( R.drawable.origin );
+        m_origin = res.getDrawable( R.drawable.ic_origin );
 
         m_prefs = CommonPrefs.get( m_context );
         m_playerColors = m_prefs.playerColors;

xwords4/android/app/src/main/res/drawable/ic_origin.xml

@@ -0,0 +1,22 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="200dp"
+    android:height="200dp"
+    android:viewportWidth="200"
+    android:viewportHeight="200">
+  <path
+      android:pathData="M24.342,25.375 L177.8,173.542v0"
+      android:strokeAlpha="1"
+      android:strokeLineJoin="miter"
+      android:strokeWidth="20.95265579"
+      android:fillColor="#00000000"
+      android:strokeColor="#000000"
+      android:strokeLineCap="butt"/>
+  <path
+      android:pathData="M177.8,25.375 L24.342,173.542v0"
+      android:strokeAlpha="1"
+      android:strokeLineJoin="miter"
+      android:strokeWidth="20.95265579"
+      android:fillColor="#00000000"
+      android:strokeColor="#000000"
+      android:strokeLineCap="butt"/>
+</vector>

xwords4/android/img_src/origin.svg

@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="200mm"
+   height="200mm"
+   viewBox="0 0 200 200"
+   version="1.1"
+   id="svg1593"
+   inkscape:version="0.92.3 (2405546, 2018-03-11)"
+   sodipodi:docname="origin.svg">
+  <defs
+     id="defs1587" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="0.7"
+     inkscape:cx="-180"
+     inkscape:cy="560"
+     inkscape:document-units="mm"
+     inkscape:current-layer="layer1"
+     showgrid="true"
+     inkscape:window-width="1920"
+     inkscape:window-height="1016"
+     inkscape:window-x="0"
+     inkscape:window-y="27"
+     inkscape:window-maximized="1">
+    <inkscape:grid
+       type="xygrid"
+       id="grid6508" />
+  </sodipodi:namedview>
+  <metadata
+     id="metadata1590">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(0,-97)">
+    <path
+       style="fill:none;stroke:#000000;stroke-width:20.95265579;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       d="M 24.341669,122.375 177.80002,270.54167 v 0"
+       id="path6510"
+       inkscape:connector-curvature="0" />
+    <path
+       style="fill:none;stroke:#000000;stroke-width:20.95265579;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
+       d="M 177.80002,122.375 24.341669,270.54167 v 0"
+       id="path6512"
+       inkscape:connector-curvature="0" />
+  </g>
+</svg>