Merged PR 167: Add Flex and fix bugs (read desc)

Note: The branch name does not fit the new features.

- Implement Flex with simplex
- Enable rigid body by default (removed IsRigidBody property) <=== possibly a bad idea
- Sort children in add and update properties
- Implement MaxWidth
- Add more docs

Fixes :
- .env.production url
- Symbols: not blocking the linked container when the parent is moving

src/Components/Editor/Behaviors/SymbolBehaviors.ts

@@ -1,9 +1,12 @@
 import { IContainerModel } from '../../../Interfaces/IContainerModel';
 import { ISymbolModel } from '../../../Interfaces/ISymbolModel';
+import { applyParentTransform } from '../../../utils/itertools';
 import { restoreX, transformX } from '../../../utils/svg';
 
 export function ApplySymbol(container: IContainerModel, symbol: ISymbolModel): IContainerModel {
   container.properties.x = transformX(symbol.x, symbol.width, symbol.config.XPositionReference);
   container.properties.x = restoreX(container.properties.x, container.properties.width, container.properties.XPositionReference);
+  const [x] = applyParentTransform(container.parent, container.properties.x, 0);
+  container.properties.x = x;
   return container;
 }