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/Interfaces/IContainerProperties.ts

@@ -1,5 +1,6 @@
 import * as React from 'react';
 import { XPositionReference } from '../Enums/XPositionReference';
+import { IMargin } from './IMargin';
 
 /**
  * Properties of a container
@@ -8,6 +9,9 @@ export default interface IContainerProperties {
   /** id of the container */
   id: string
 
+  /** type matching the configuration on construction */
+  type: string
+
   /** id of the parent container (null when there is no parent) */
   parentId: string
 
@@ -23,6 +27,9 @@ export default interface IContainerProperties {
   /** vertical offset */
   y: number
 
+  /** margin */
+  margin: IMargin
+
   /**
    * Minimum width (min=1)
    * Allows the container to set isRigidBody to false when it gets squeezed
@@ -30,18 +37,23 @@ export default interface IContainerProperties {
    */
   minWidth: number
 
+  /**
+   * Maximum width
+   */
+  maxWidth: number
+
   /** width */
   width: number
 
   /** height */
   height: number
 
-  /** true if rigid, false otherwise */
-  isRigidBody: boolean
-
   /** true if anchor, false otherwise */
   isAnchor: boolean
 
+  /** true if flex, false otherwise */
+  isFlex: boolean
+
   /** Horizontal alignment, also determines the visual location of x {Left = 0, Center, Right } */
   XPositionReference: XPositionReference