Updater script for MiSTer

The script updates all MiSTer cores, including menu.rbf and the main MiSTer Linux executable; it updates scaler filters and GameBoy palettes; it can (experimental and risky) optionally update the whole Lynux system. Simply put mister_updater.sh in your SD and launch it through MiSTer main menu OSD (press F12 and then Scripts). You can edit it (Win users, please use Notepad++) in order to change some self-explanatory variables (paths, deleting old cores, etc.). I take no responsibility for any data loss or anything, if your DE10-Nano catches fire it’s up to you: use the script at your own risk.