Issue #50: add icon for historic=fort.

map_machine/icons/icons.svg

@@ -24419,8 +24419,8 @@
        rx="0"
        ry="0" />
     <path
-       id="path12334"
-       style="opacity:1;fill:#0000ff;fill-opacity:1;stroke:none;stroke-width:0.1;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
+       id="fort"
+       style="opacity:1;fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.1;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1"
        d="m 308,337 v 2 h 8 v -2 h -2 v 1 h -1 v -1 h -2 v 1 h -1 v -1 z m 1,3 -0.5,3 H 307 l -0.5,-1 H 305 v 8 h 6 v -3 c 0,-0.554 0.446,-1 1,-1 0.554,0 1,0.446 1,1 v 3 h 6 v -8 h -1.5 l -0.5,1 h -1.5 l -0.5,-3 z m -1,5 c 0.554,0 1,0.446 1,1 v 2 h -2 v -2 c 0,-0.554 0.446,-1 1,-1 z m 8,0 c 0.554,0 1,0.446 1,1 v 2 h -2 v -2 c 0,-0.554 0.446,-1 1,-1 z"
        sodipodi:nodetypes="ccccccccccccccccccccsssccccccccssccssssccss" />
     <path

map_machine/scheme/default.yml

@@ -310,6 +310,8 @@ node_icons:
     - tags: {historic: castle}
       location_restrictions: {include: [jp]}
       shapes: [japan_castle]
+    - tags: {historic: fort}
+      shapes: [fort]
     - tags: {shop: mall}
       shapes: [bag]
     - tags: {shop: mall, building: "yes"}