We'll use BURP for backups, just like the old Home Assistant server.
Note that Portage cannot correctly set the ownership of files when
installing to an alternate $ROOT. To work around this, we replace the
`fowners` function for the *app-backup/burp* ebuild with a no-op, and
then set the permissions of the relevant files using SquashFS
pseudo-file definitions. Relatedly, we're omitting the files and
directories used by the server-side of BURP.
The `build.packages` and `install.packages` files in the CONFIGDIR now
only need to include *additional* packages to install. The packages
*required* for Aimee OS are always installed, listed in the
corresponding files in the source directory.
In effort to support different builds of Aimee OS using the same
scripts, without necessarily having to fork this repository, the build
system now supports a `CONFIGDIR` setting. When this variable is set,
files defining the target environment, such as the lists of packages to
install, the kernel configuration, the Portage configuration, etc. are
found in the path it specifes.
The reference build, for the Home Assistant Yellow board, is configured
in the `yellow` directory. To build it, run:
```sh
CONFIGDIR=yellow ./vm-build.sh
```