Make all operations on elements array immutable (#283)

* Make scene functions return array instead of mutate array

- Not all functions were changes; so the given argument was a new array to some

* Make data restoration functions immutable

- Make mutations in App component

* Make history actions immutable

* Fix an issue in change property that was causing elements to be removed

* mark elements params as readonly & remove unnecessary copying

* Make `clearSelection` return a new array

* Perform Id comparisons instead of reference comparisons in onDoubleClick

* Allow deselecting items with SHIFT key

- Refactor hit detection code

* Fix a bug in element selection and revert drag functionality

Co-authored-by: David Luzar <luzar.david@gmail.com>

src/element/resizeTest.ts

@@ -34,7 +34,7 @@ export function resizeTest(
 }
 
 export function getElementWithResizeHandler(
-  elements: ExcalidrawElement[],
+  elements: readonly ExcalidrawElement[],
   { x, y }: { x: number; y: number },
   { scrollX, scrollY }: SceneScroll
 ) {