Validate firewall rule advanced options requirements

Checks that the user has selected a TCP Pass rule etc when using the state-related advanced options. Validates as per the checks that are applied in filter.inc when generating the actual pf rules.
Forum discussion: http://forum.pfsense.org/index.php/topic,64653.15.html
Bug report #3098
This implements validation without changing what the real code actually does (filter.inc). Then there can be discussion about relaxing the constraints (allowing various state-related advanced options on UDP...) and what release that would go into (Main for 2.2 or pushing it into 2.1...?) At least this change gets the validation "documented" in the GUI.
This pull request is for the Main version. I will also submit a request for the 2.1 branch, because I suspect it will not merge back cleanly to 2.1.