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.test.tsx

@@ -22,6 +22,7 @@ describe.concurrent('Properties', () => {
   it('Some properties, change values with dynamic input', () => {
     const prop: IContainerProperties = {
       id: 'stuff',
+      type: 'type',
       parentId: 'parentId',
       linkedSymbolId: '',
       displayedText: 'stuff',
@@ -30,8 +31,10 @@ describe.concurrent('Properties', () => {
       width: 1,
       height: 1,
       minWidth: 1,
+      maxWidth: Infinity,
+      margin: {},
       XPositionReference: XPositionReference.Left,
-      isRigidBody: false,
+      isFlex: false,
       isAnchor: false
     };