Sketchify 36 - part 1

First iteration of sketchify for 3.6

Major restructuring of the code. For now the functionality remains basically the same: `sketchify file.cf`, and answer the interactive prompts. The restructuring enables future functionality, such as using sketchify to update existing sketches.

New hidden feature: `sketchify file.cf script.txt`, lines will be read from `script.txt` and used to automatically answer the prompts. Useful for testing.