[matter] return exit_st out of matter_main() and main() instead of raising SystemExit
[matter] add --pretend flag, makes possible to run matter in pretend mode directly
[matter] show the list of uninstalled packages at the end of the execution
[matter] fix handling of --pretend in build_args, myopts is not available at that stage
[matter] fix --pretend behaviour. Matter is required to return after dep calculation.
[matter] print particle file name together with particle execution status
[matter] fixup ACCEPT_KEYWORDS handling, broken due to weirdo and whacky Portage API
Release Entropy 168
Tagging Entropy version 168
[entropy.server] add drained and merged repositories dependencies testing

It happens that during our workflow, we bump packages into overlay repositories
like sabayon-limbo and sabayon-hell. However, potential dependencies issues
may pop up only when repositories are merged (their content drained) into
others. This features assumes that repositories are listed in order of priority,
where the first one is the base repo and others are layers on top of the first one.
[entropy.server] fix reversed() usage
[entropy.server] improve output of drained_dependencies_test()
[entropy.server] improve output of drained_dependencies_test() even more
[entropy.server] tweak merged_repositories_test() a bit more
[entropy.server] tweak output() in merged_dependencies_test()
[entropy.server] last output tweaks to drained_repositories_test()
[entropy.server] other tweaks to drained_dependencies_test()
[entropy.server] drop one more useless output()
[matter] implement support for the "unmerge: yes/no" parameter
Release Entropy 169