~BugFix! In APT_POST_INVOKE_CLEANUP macro. Removing shared 'locale' folder was bit too aggressive.
~ PACKAGE_INSTALLED now checks for package dependencies when building on a debian system.
~ Perl grep not available on alpine therefore any 'grep -P ...' invocation has now been replaced by 'perl -ni ...'
~ fakeroot environment is now used only when build is running natively (not in a container) and not by root user. The 'arch' argument has been added explicitly to avoid an error selecting the wrong architecure when running on _alpine_.

~ 'prerequisites' target now uses the PACKAGE_INSTALLED macro to make it available for both as a dependency or as a direct call (even without any target).
~ Sanity checks for OWNER revised.

~ BugFix! 'clean' target still removed the base image with an old name which isn't created at all since the change in the last commit. This has been fixed by using the new tag naming.
~ APT config revised, image size further reduced.
~ Rule added in 'apt.conf.d' to clean more aggressively unnecessary files like man and info pages, locales and log files. Additional paths may be set in APT_POST_INVOKE_CLEANUP variable.
~ This is now already done in the base image before running the second stage of debootstrap.
~ Makefile prerequisites revised to give a precise warning about missing packages.

~ TAG_DEPENDENCY call added. It allows to link GNU/make targets directly to the existence of a docker image without an intermediate file. This way it's possible to determine wether an image needs a build when the corresponding 'Dockerfile' has changed.
~ Any image produced by the 'dockyard' project now prefixes it's image tag names with 'dyd/...' to avoid conflicting image names from forgein repositories.

~ New global 'Makefile' with a bunch of simple docker functionality primarily for building containers added.
~ New 'debian' container added. It builds two plain debian images. A base container from scratch (not meant to be used directly) on which a general-purpose debian system container is build without any custom tweaks serving as a base for other images.
~ New 'resolver/Makefile' added. This is just work in progress.