Add a --set command line option to set/override a configuration value.
When setting a sequence value, check for an existing node.

This makes --set af-packet.0.threads=X do what you expect by
looking for the sequence node before setting.
fileext: make case insensitive

Change keyword to be case insensitive when matching.

Ticket #597.
profiling: end profiling tunnel packets inside lock

End profiling inside the lock for a tunnel packet as otherwise another
thread may already free the packet while the profiling code runs.

SEGV's observed and now gone.
Fix address parsing issues

Fix issue where negating a range containing a negation would fail.

E.g. HOME_NET: [192.168.0.0/16,!192.168.10.0], can be used in a rule
     as !$HOME_NET.

Also, fix another parsing issue:

If the negation range would be bigger than the 'positive' range, parsing
wouldn't be correct. Now this case is rejected.

E.g. [192.168.1.3,!192.168.0.0/16] is now explicitly rejected

Ticket 1079.