Added footsteps, new tree, various other tweaks

addons/proton_scatter/icons/square_handle.svg

@@ -0,0 +1,76 @@
+<?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="16"
+   height="16"
+   viewBox="0 0 4.2333332 4.2333335"
+   version="1.1"
+   id="svg3719"
+   inkscape:version="0.92.4 5da689c313, 2019-01-14"
+   sodipodi:docname="handle.svg">
+  <defs
+     id="defs3713" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="22.4"
+     inkscape:cx="8.25368"
+     inkscape:cy="6.4723671"
+     inkscape:document-units="mm"
+     inkscape:current-layer="layer1"
+     showgrid="true"
+     units="px"
+     inkscape:window-width="2524"
+     inkscape:window-height="1050"
+     inkscape:window-x="36"
+     inkscape:window-y="0"
+     inkscape:window-maximized="1">
+    <inkscape:grid
+       type="xygrid"
+       id="grid3723" />
+  </sodipodi:namedview>
+  <metadata
+     id="metadata3716">
+    <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,-292.76665)">
+    <rect
+       id="rect3721"
+       width="4.2333331"
+       height="4.228621"
+       x="1.0782784e-09"
+       y="292.77136"
+       style="stroke-width:0.26458332" />
+    <rect
+       style="fill:#ffffff;stroke-width:0.26458332"
+       id="rect3725"
+       width="3.175"
+       height="3.175"
+       x="0.52916664"
+       y="293.29581" />
+  </g>
+</svg>