Add NumericInputWidget for use with Buefy themes

uses a Vue.js component for better logic encapsulation

tailbone/static/js/tailbone.buefy.numericinput.js

@@ -0,0 +1,38 @@
+
+const NumericInput = {
+    template: [
+        '<b-input',
+        ':name="name"',
+        ':value="value"',
+        '@keydown.native="keyDown"',
+        '@input="valueChanged"',
+        '>',
+        '</b-input>'
+    ].join(' '),
+
+    props: {
+        name: String,
+        value: String,
+        allowEnter: Boolean
+    },
+
+    methods: {
+
+        keyDown(event) {
+            // by default we only allow numeric keys, and general navigation
+            // keys, but we might also allow Enter key
+            if (!key_modifies(event) && !key_allowed(event)) {
+                if (!this.allowEnter || event.which != 13) {
+                    event.preventDefault()
+                }
+            }
+        },
+
+        valueChanged(value) {
+            this.$emit('input', value)
+        }
+
+    }
+}
+
+Vue.component('numeric-input', NumericInput)