add backoff to arrow-up and arrow-bar-up

Author: archmoj

src/components/drawing/symbol_defs.js

@@ -583,6 +583,7 @@ module.exports = {
             var ry = round(r * 2, 2);
             return align(angle, standoff, 'M0,0L-' + rx + ',' + ry + 'H' + rx + 'Z');
         },
+        backoff: 1,
         noDot: true
     },
     'arrow-down': {
@@ -627,6 +628,7 @@ module.exports = {
             var ry = round(r * 2, 2);
             return align(angle, standoff, 'M-' + rx + ',0H' + rx + 'M0,0L-' + rx + ',' + ry + 'H' + rx + 'Z');
         },
+        backoff: 1,
         needLine: true,
         noDot: true
     },

test/image/baselines/z-marker-standoff_auto-backoff.png

@@ -6,9 +6,13 @@
                 "width": 5
             },
             "marker": {
+                "line": {
+                    "width": 2,
+                    "color": "darkblue"
+                },
                 "standoff": [5, 20, null, 20, 10],
                 "angleref": "previous",
-                "symbol": "arrow",
+                "symbol": "arrow-bar-up",
                 "size": 20
             },
             "x": [
@@ -213,7 +217,7 @@
             "marker": {
                 "standoff": [5, 20, null, 20, 10],
                 "angleref": "previous",
-                "symbol": "arrow",
+                "symbol": "arrow-up",
                 "size": 20
             },
             "r": [