Fixups

features:
- portage now builds binary packages by default
- portage now saves all logs it produces

unfeatures:
- remove purging code (#57)

misc:
- both purge and destroy now return an error so that whoever has them in a script (doubt anyone does) can notice it.
- readibility improvements
- replace more if-then-fi error checking with || die
- misc bugfixes


btw. ARM containers work*
*with some external help