Creating a text near the center of a shape should put it in the center (#270)

* Snap to element center

* Fixed typo

* Added comment

* Reduced threshold to 30

* Skip snapping if alt key is pressed

* Fixed creating text with shape tool

src/scene/index.ts

@@ -14,5 +14,10 @@ export {
   restoreFromLocalStorage,
   saveToLocalStorage
 } from "./data";
-export { hasBackground, hasStroke, getElementAtPosition } from "./comparisons";
+export {
+  hasBackground,
+  hasStroke,
+  getElementAtPosition,
+  getElementContainingPosition
+} from "./comparisons";
 export { createScene } from "./createScene";