Change Frame allocations from heap to stack.
Refactor to drive logic off of grid boundaries rather than extant files.

- Main logic now finds minimum and maximum coordinate values from
  available files, and processes entire grid these define. These allows
  adding logic for filling backgrounds of frames without screens.
- Handle negative coordinates.
- Refactor and cleanup for general readibility.
- Add stitch-test script.
Rename asset directories and outputs and pick more representative test assets.