New constant and new BackgroundProcess action

allows to remove rules in background
moved rules management in background
Allow local connections at boot time

Orbot may start before orwall, thus we may get some troubles.
Corrected iptables rules - they were a bit too strong.

Problems:
- DNS queries are made by UID 0
- missing related,established grant for INPUT chain

Hence, we have to allow the whole system to make DNS queries, though it
has to know about UDP:5400 (qhich isn't that hard…)

This may be a flaw in the system, but we cannot do anything against that
for now.