Implement webworker for save operation + Limit the history size (#29)

- Implement webworker for save operation
- Limit the history size

Reviewed-on: https://git.siklos-chaneru.duckdns.org/Siklos/svg-layout-designer-react/pulls/29

src/utils/default.ts

@@ -39,3 +39,5 @@ export const DEFAULT_MAINCONTAINER_PROPS: IProperties = {
 };
 
 export const NOTCHES_LENGTH = 4;
+
+export const MAX_HISTORY = 200;