By default this feature is enabled. On the first run it will copy (if
exists) databases from filesystem to local cache (one per each
architecture). Later it will use this cache for all alpm operations. In
order to update this cache, some commands (mainly package building)
provide `-y`/`--refresh` option which has same semantics as pacman -Sy
does.
Note however that due to extending `Pacman` class some methods were
renamed in order to be more descriptive:
* `Pacman.all_packages` -> `Pacman.packages`
* `Pacman.get` -> `Pacman.package_get`
This commit also adds multilib repository to the default docker image
which was missed.
* fix dependency list for packaging
* add ability to rebuild everything or skip specific things during an
update
* add architecture configuration
* fix file and directory removals
