Implement event model in C++

Filtering events in JS is too slow with >20,000 events. This moves the
event data model into C++.

Fields/Bool.qml

@@ -4,14 +4,13 @@ import QtQuick 2.12
 import QtQuick.Controls 2.13
 
 Row {
-    id: control
     width: parent.width
 
-    property var definition
+    property var model
     property alias value: input.checked
 
     Keys.onPressed: {
-        if (event.text === definition.key) {
+        if (event.text === model.key) {
             value = !value
             event.accepted = true
         }