Use FIREHOL_ESTABLISHED_ACTIVATION_ACCEPT

In non fast-activation mode and if set to 1 (the default), will emit
temporary rules to allow established traffic to continue even when
the activation policy is DENY. The temporary rules are deleted when
the firewall is complete.
Improve worst-case error handling

 - When the generated script fails but we don't know why
   we now leave the temporary files behind
 - Ensure execution happens in current shell context so we don't
   lose variables defined as part of the configuration

Conflicts:
	sbin/firehol.in
Use flock(1) instead of lockfile(1)

- Introduces a dependency on util-linux (rather than procmail)
- Exit immediately if we cannot create lockfile when using flock
Make FIREHOL_FAST_ACTIVATION environment-settable

Especially useful when running comparison tests
Ensure ChangeLog and NEWS versions are in sync
Merge pull request #13 from ktsaou/patches-noipv6

Remaining non-IPv6 patches