new update script

[tehn]

new update method attached. forthcoming edits to norns menu lua code.

here's the new method, which will allow for more error reporting and understanding of what's going on.

• update files have a custom extension (so browsers won't auto-extract) ie 181101.norns
• user puts update file in ~/update/ via SFTP or
• user can put file on USB drive root
• user manually runs this update file by logging in via SSH or serial:

./update.sh

• checks free disk space (point of failure earlier)
• checks versions and only copies/performs when appropriate
• cleans up (deletes all update files) afterwards

[tehn]

@pq thanks! all edits made

[tehn]

more generally, i'm holding off on assuming this is a good approach overall.

going to sit with it for a few days. suggestions highly welcome.