Merged PR 179: Fix bugs about flex and context menu (see desc) + disable hard rigid behavior + add missing properties to form + Clean up css

- Clean up some css class
- Fix wrong order when applying flex
- Fix Replace behavior not working because previous container was still existing
- Disable hard rigid behavior which disallow two container to overlap
- Add ENABLE_FLEX, ENABLE_HARD_RIGID ENABLE_SWAP
- Add missing form properties with dimensions
- Update readme

src/Components/Editor/Behaviors/RigidBodyBehaviors.ts

@@ -9,6 +9,7 @@
 import Swal from 'sweetalert2';
 import { IContainerModel } from '../../../Interfaces/IContainerModel';
 import { ISizePointer } from '../../../Interfaces/ISizePointer';
+import { ENABLE_HARD_RIGID } from '../../../utils/default';
 
 /**
  * "Transform the container into a rigid body"
@@ -23,7 +24,11 @@ export function ApplyRigidBody(
   container: IContainerModel
 ): IContainerModel {
   container = ConstraintBodyInsideParent(container);
-  container = ConstraintBodyInsideUnallocatedWidth(container);
+
+  if (ENABLE_HARD_RIGID) {
+    container = ConstraintBodyInsideUnallocatedWidth(container);
+  }
+
   return container;
 }