Merged PR 17: Implement rigid body Fix multiple bugs

Implement rigid body

Fix saveload bug: having null elements
Fix events being duplicated and not being removed

src/Components/App/MenuActions.ts

@@ -22,6 +22,7 @@ export function NewEditor(
           y: 0,
           width: configuration.MainContainer.Width,
           height: configuration.MainContainer.Height,
+          isRigidBody: false,
           fillOpacity: 0,
           stroke: 'black'
         }
@@ -34,6 +35,7 @@ export function NewEditor(
         history:
           [
             {
+              LastAction: '',
               MainContainer,
               SelectedContainer: MainContainer,
               SelectedContainerId: MainContainer.properties.id,