* Allow to specify a custom username in "pmbootstrap init"
* Build chroots have "pmos" instead of "user" as username now
* Installation user UID is 1000 now (as in all other Linux distributions)
* Adjust autologins
* postmarketos-base: enable wheel group for sudo, removed previous sudoers file
* Implement safe upgrade path:
We save the version of the work folder format now, in $WORK/version.
When this file does not exist, it defaults to 0.
In case it does not match the currently required version
(pmb.config.work_version), then ask the user if it should
automatically be upgraded.
I've replaced all instances in the code of `os.path.abspath`
with `os.path.realpath`, as this does the same as `abspath`
plus resolving symlinks.
See also: https://stackoverflow.com/a/40311142
* Refactored `umount_all` to get the list of folders to be umounted from
`umount_all_list`, so we can test that function in a test case.
* Adjusted `umount_all_list` to return the deep folder levels first
* Added a testcase for that
* Remove redundant calls to `umount_all()` (which were from a time before
`pmbootstrap` was released, in which failing commands did not cause
`pmbootstrap` to raise an exception)
Pablo Castellano
Oliver Smith