Bug Fixes and Improvements

Bug Fixes
1 Keyboard dismissing via dismiss button on keyboard (button is located on bottom right of keyboard) now reinstates the canvasWindow to the proper size.
2 Newly created notes are introduced into physics engine before touch gestures attached to the notes. This prevents users with fast reflex from moving notes before the physics engine even knows of their existence. This solves the problem of having users moving notes into walls and having the notes getting stuck in the walls.

Improvements
1 Pragma marked editDiagramViewController to make it easier for developers to navigate this 600 ~ 700 LOC class.
2 Conveyed grid line drawing to Grand Central Dispatch. Grid line drawing is a computationally intensive operation that noticeably halts the UI if performed on the main thread.