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/IEditorState.tsx

@@ -0,0 +1,8 @@
+import { IConfiguration } from './IConfiguration';
+import { IHistoryState } from './IHistoryState';
+
+export interface IEditorState {
+  history: IHistoryState[]
+  historyCurrentStep: number
+  configuration: IConfiguration
+}