slight optimizations: avoid unnecessary writes

but this happens only during config load, so no real gain
refactor property-based filter decoding

among others, provides *much* better error messages to user
bugfix: invalid property filter was not properly disabled in ruleset

Note that this bugfix introduces a very slight memory leak, which is
cosmetic, as it just holds data until termination that is no longer
needed. It is just the part of the config that was invalid. We will
"fix" this "issue" in the devel version first, as the fix is a bit
too intrusive to do without hard need in the stable version.
Merge branch 'v7-stable'

Conflicts:
	runtime/conf.c