Miyoo Flip BaseOS v1.2.0

Read the installation instructions in INSTALL.md.

This BaseOS release includes some further improvements to work better with SpruceOS, made collaboration with the development team, plus some other improvements for the update process:

• refactoring of rcK, with better shutdown behavior, including unmounting of /usr overlays and swapoff
• do not repair a FAT partition that would be in use
• do not update partitions that are unchanged when updating from a .bosupd file
• allow proper update from a pre-release

The last fix is important for users who updated to the last beta version. If you have it installed, you will not be able to update automatically to the latest update using the .bosupd file. This is because a bug was causing pre-releases to be considered more recent than stable releases by the update script. If you are in this case, you'd need to do a full re-flash of the SD card. Make sure to do a back-up if you had anything under the BASEOS partition.