implemented deletion of item properties

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

frontend/src/routes/stock/ItemProps.svelte

@@ -19,7 +19,9 @@
         return a.name.localeCompare(b.name);
     }
 
-    async function onclick(){
+    async function onsubmit(ev){
+        ev.preventDefault();
+        ev.stopPropagation();
         const url = api('stock/property');
         const data = {
             item : {
@@ -40,6 +42,7 @@
             item.properties.push(prop);
             yikes();
         } else error(res);
+        return false;
     }
 
     async function patch(key,newVal){
@@ -95,13 +98,15 @@ Code: <LineEditor type="span" editable={true} value={item.code} onSet={v => patc
                 {/if}
             </td>
             <td>
+                <form {onsubmit}>
                 <input type="text" placeholder="value" bind:value={add_prop.value} />
                 {#if !add_prop.existing_prop_id}
                 <input type="text" placeholder="unit" bind:value={add_prop.new_prop.unit} />
                 {:else}
                 {properties.filter(p => p.id == add_prop.existing_prop_id)[0].unit}
                 {/if}
-                <button {onclick}>{t('save')}</button>
+                <button>{t('save')}</button>
+                </form>
             </td>
         </tr>
     </tbody>