Add Linux 3.0 support.
Update changelog noting support for Linux 3.0
Fix major regressions in the Makefile from commit e0640add.

This restores the ability to install into a staging directory (DESTDIR) which
is required to be able to build a .deb
Fix IPv6 support.

Rulesets run in a subshell where dual_tables was not defined, only IPv4 rules
were getting loaded.

Move all iptables handling code into a separate file so it can easily be
sourced by ruleset.functions (used in the ruleset subshell) and the main
firewall script itself.

Also improve behaviour when ip6tables is unavailable. Previously we would
crash, now we attempt to load support for ip6tables (as we do for ip4tables)
and fail gracefully without exiting if ip6tables support is unavailable. A
warning error is printed if ip6tables support is unavailable but IPv6 specific
rules are found.
Ensure errors are correctly propogated out of dual_tables.
Prevent duplicate logging of v6 support messages.
Expose table flush support.

* Fix flushing logic to support IPv6, and add the ability to reset policies
  after flushing.
* Expose the ability to flush tables when called with -f.
Release bearwall 1.06.
Replace PCRE syntax for matching IP addresses with Posix extended syntax to
allow bearwall to run on systems where grep is supplied by busybox (e.g.
openwrt).
Remove unnecessary whitespace.
Fix up Makefile to support building a .deb and being installed standalone.

This commit keeps the ability of installing to a staging directory for making a .deb as well as supporting standalone installs via "make install".
Tidied up the supplied class files.

I've tidied up the whitespace and fixed up the comments a little bit.