Simplifiy <dougal-context-menu/> model

lib/www/client/source/src/components/context-menu.vue

@@ -1,6 +1,7 @@
 <template>
   <v-menu
-    v-model="show"
+    :value="value"
+    @input="(e) => $emit('input', e)"
     :position-x="absolute && x || undefined"
     :position-y="absolute && y || undefined"
     :absolute="absolute"
@@ -62,7 +63,6 @@ export default {
 
   data () {
     return {
-      show: false,
       x: 0,
       y: 0,
       showSubmenu: false