Create the tag when focusing out of the input

This is mainly because i sometimes think that the tag is accepted just
because it is there in the input, but actually it is not being used at
all.  I fear more people would do the same mistake.

web/static/numerus.js

@@ -339,6 +339,12 @@ class Tags extends HTMLDivElement {
                     break;
             }
         });
+        window.addEventListener('focusin', (e) => {
+            if (this.contains(e.target)) return;
+            if (e.target.value.trim() !== '') {
+                this.createTag();
+            }
+        });
 
         // Must come after the search input
         this.tagList.append(this.label);