Snap everything to grid (#315)

* Implement snap to grid

- Moves positioning logic to LGraph
- Simplifies code
- Adds Pointer API to alt-clone node
- Removes always_round_positions, replaced by always snap to grid (default size is 1 when always snapping)

Fix refator error

* Fix group items snapped without group

* Allow snapping of all items

- Add snapToGrid to Positionable
- Impl. on all types
- Deprecated: alignToGrid is now a wrapper

* Fix test import alias, update expectations

* Prevent desync of before / after change events

Adds ability to perform late binding of finally() during drag start.

* nit - Refactor

* Fix unwanted snap on node/group add

* nit - Doc

* Add shift key state tracking for snap to grid

Private impl., no state API as yet.

* Add snap guides rendering

Nodes, reroutes

* Optimisation - reroute rendering

 Fixes exponential redraw

* Add snap guidelines for groups

src/utils/collections.ts

@@ -1,4 +1,5 @@
-import type { Parent } from "../interfaces"
+import type { Parent, Positionable } from "../interfaces"
+import { LGraphNode } from "@/LGraphNode"
 
 /**
  * Creates a flat set of all items by recursively iterating through all child items.
@@ -16,3 +17,14 @@ export function getAllNestedItems<TParent extends Parent<TParent>>(items: Readon
         item.children?.forEach(x => addRecursively(x, flatSet))
     }
 }
+
+/**
+ * Iterates through a collection of {@link Positionable} items, returning the first {@link LGraphNode}.
+ * @param items The items to search through
+ * @returns The first node found in {@link items}, otherwise `undefined`
+ */
+export function findFirstNode(items: Iterable<Positionable>): LGraphNode | undefined {
+    for (const item of items) {
+        if (item instanceof LGraphNode) return item
+    }
+}