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/ContainerProperties/ContainerProperties.tsx

@@ -1,4 +1,5 @@
 import React from 'react';
+import { PropertyType } from '../../Enums/PropertyType';
 import IContainerProperties from '../../Interfaces/IContainerProperties';
 import { ISymbolModel } from '../../Interfaces/ISymbolModel';
 import ContainerForm from './ContainerForm';
@@ -6,7 +7,7 @@ import ContainerForm from './ContainerForm';
 interface IPropertiesProps {
   properties?: IContainerProperties
   symbols: Map<string, ISymbolModel>
-  onChange: (key: string, value: string | number | boolean, isStyle?: boolean) => void
+  onChange: (key: string, value: string | number | boolean, type?: PropertyType) => void
 }
 
 export const Properties: React.FC<IPropertiesProps> = (props: IPropertiesProps) => {