Merged PR 162: Implement symbols and other stuff (see desc)

Implement symbols
- Add, Remove, Select Container
- Form
- Link with container
- Symbol behavior application to container (move to x with xpositionreference)

Important changes
- Remove SelectedContainer from HistoryState, meaning that it will be slower for each load but will be faster for each operations* (SetHistory, SelectContainer, DeleteContainer, SymbolOperations)
- ElementsSidebar now opens with isSidebarOpen meaning that both sidebar will open on toggle
- Moved camelize, transformX, restoreX to different modules (stringtools.ts, svg.ts)

src/Components/Editor/Behaviors/RigidBodyBehaviors.ts

@@ -19,7 +19,7 @@ import { ISizePointer } from '../../../Interfaces/ISizePointer';
  * @param container Container to apply its rigid body properties
  * @returns A rigid body container
  */
-export function RecalculatePhysics(
+export function ApplyRigidBody(
   container: IContainerModel
 ): IContainerModel {
   container = constraintBodyInsideParent(container);
@@ -231,14 +231,15 @@ function getAvailableWidths(
   const width = container.properties.width;
   let unallocatedSpaces: ISizePointer[] = [{ x, width }];
 
-  // We will only uses containers that also are rigid or are anchors
-  const solidBodies = container.children.filter(
-    (child) => child.properties.isRigidBody || child.properties.isAnchor
-  );
+  for (const child of container.children) {
+    if (unallocatedSpaces.length < 1) {
+      return unallocatedSpaces;
+    }
 
-  for (const child of solidBodies) {
     // Ignore the exception
-    if (child === exception) {
+    // And we will also only uses containers that also are rigid or are anchors
+    if (child === exception ||
+      (!child.properties.isRigidBody && !child.properties.isAnchor)) {
       continue;
     }
     const childX = child.properties.x;