Implement events for external use + Rename interfaces with a I prefix + add some documentation (#26)

Implement events for external use
Rename interfaces with a I prefix
Add some documentation

Co-authored-by: Eric NGUYEN <enguyen@techform.fr>
Reviewed-on: https://git.siklos-chaneru.duckdns.org/Siklos/svg-layout-designer-react/pulls/26

src/Interfaces/IProperties.ts

@@ -0,0 +1,11 @@
+import * as React from 'react';
+import { XPositionReference } from '../Enums/XPositionReference';
+
+export default interface IProperties extends React.CSSProperties {
+  id: string
+  parentId: string | null
+  x: number
+  y: number
+  isRigidBody: boolean
+  XPositionReference?: XPositionReference
+}