Changes since 1.3.10

1. Added TCP flags checking.

2. Accomodate bash clones like dash and ash

3. Added some comments in the policy chain creation/population logic.

4. Check for fw->fw rules.

5. Allow 'all' in rules.

6. Add reverse GRE rules for PPTP server and clients.

7. Add warning to tcrules file.

8. Add warning to policy file that fw->fw policies aren't allowed.