Add context change toast.

app/templates/corpora/analyse_corpus.html.j2

@@ -330,6 +330,10 @@
   // event triggered on context select change and also if pagination is clicked
   function changeContext(event) {
     // newValue = event.target.value;  // cannot use this anymore due to reuse of this function in the above paginationElements eventListener
+    console.log(event);
+    if (event.type === "change") {
+      nopaque.toast("Updated context per match!");
+    }
     var contextPerItemElement = document.getElementById("context");
     newValue = contextPerItemElement.value;
     console.log(newValue);