[WIP] Add Back Image Selection

[0xcaff]

TODO:

• [x] Complete Implementation
• [x] Don't Assume Top Left and Bottom Right
• [ ] Add Stream Polyfill
• [x] Add Nicer Loading
• [ ] Add Demo Images
• [ ] High DPI Canvas
• [ ] Add Remove Extra Nodes Step
• [ ] Use Fancy Buttons
• [ ] Removed Nodes As Selected
• [ ] Performance

Closes #62