add magnetometer clock info

apps/clkinfomag/ChangeLog

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+0.01: New Widget!

apps/clkinfomag/clkinfo.js

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+(function() {
+  var heading, cnt;
+  function magHandler(m) {
+    var h = m.heading;
+    if (isNaN(heading) || isNaN(h))
+      heading = h;
+    else {
+      // Average
+      if (Math.abs(heading-h)>180) {
+        if (h<180 && heading>180) h+=360;
+        if (h>180 && heading<180) h-=360;
+      }
+      heading = heading*0.8 + h*0.2;
+      if (heading<0) heading+=360;
+      if (heading>=360) heading-=360;
+    }
+    // only draw 1 in 2 to try and save some power!
+    if (!(1&cnt++)) ci.items[0].emit('redraw');
+  }
+  var ci = {
+    name: "Bangle",
+    items: [
+      { name : "Compass",
+        get : function() {
+          var g = Graphics.createArrayBuffer(24,24,1,{msb:true});
+          if (isNaN(heading))
+            g.drawLine(8,12,16,12);
+          else
+            g.fillPoly(g.transformVertices([0,-10,4,10,-4,10],{x:12,y:12,rotate:-heading/57}));
+          return { text : isNaN(heading)?"--":Math.round(heading),
+                      v : 0|heading, min : 0, max : 360,
+                      img : g.asImage("string") }},
+        show : function() {
+          Bangle.setCompassPower(1,"clkinfomag");
+          Bangle.on('mag',magHandler);
+          cnt=0;
+          heading = undefined;
+        },
+        hide : function() {
+          Bangle.removeListener('mag', magHandler);
+          Bangle.setCompassPower(0,"clkinfomag");
+        },
+        run : function() { Bangle.resetCompass(); }
+      }
+    ]
+  };
+  return ci;
+}) // must not have a semi-colon!

apps/clkinfomag/metadata.json

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+{ "id": "clkinfomag",
+  "name": "Compass Clockinfo",
+  "version":"0.01",
+  "description": "Extra information to add to clock screens. When selected, displays the compass heading and an arrow pointing North",
+  "icon": "icon.png",
+  "type": "clkinfo",
+  "tags": "clkinfo,compass,mag,magnetometer",
+  "supports" : ["BANGLEJS2"],
+  "storage": [
+    {"name":"clkinfomag.clkinfo.js","url":"clkinfo.js"}
+  ]
+}