Application Editor

- [ ] Add an editor built in for positioning buttons on each layer.
- [ ] Add drag-select for buttons on a layer.
- [ ] Add editor debug mode to print out the position and width of either the selected button or drag-selected buttons on the layer.
1. Save the selected buttons on a layer in this format:
* Layer: `name`
* Buttons:
* `button name`:
* x, y, width, height
* background colour, outline colour, text colour
2. File name: `name` - `date`

No files, tests, or entry points are named, so first locate the existing application layer and button UI code. Done means providing an editor that positions buttons, supports drag-selection, offers the requested debug output, and saves the specified layer and button data to a dated file.

Written by the indexing model from the issue text.