bugfix: potential segfault during startup on invalid config

could happen if invalid actions were present, which could lead
to improper handling in optimizer.
Merge branch 'v7-stable'
imfile changes back again, but with retained format
Merge branch 'v7-stable'
doc: instructions for rotating signed files
Merge branch 'v7-stable'
fix compile problem in debug build
Merge branch 'master' into master-lookup
milestone: lookup table ready for actual load (but load not yet done)