* Add squashfs with LZ4 and LZO compression to Barebox
* Add squashfs with LZO compression to U-Boot
* Use squashfs for Linux kernel partition
Generate a squashfs image with LZO compression for the Linux kernel
partition. Adjust the boot scripts to be file system independent commands
to boot from squashfs.
* Add development build version part to version number
Add third part in the version number to indicate development builds.
Generate a default version number based on the date, e.g.
"5.6.dev20201124".
* Add GitHub Action workflow for development builds
Add another GitHub workflow for development builds. Make it triggered
only for now. The version number is generated by the workflow and
passed to all builds to make sure all builds have the same development
build version.
* Add documentation
