Firewall and configuration backup/restore features finished

Step by step the todo list gets smaller. Today the firewall WebUI and backend has been finished. Please note that firewall feature is only designed as client firewall. Everything else should be done by a real router/firewall appliance.

Also the configuration backup/restore feature has been implemented. Now it is possible to create a configuration backup and restore it later.

Add SNMP service

Today i added generic SNMP support. The MIB tree can be retrieved only, no write access. Currently only the protocol versions v1 and v2c are supported. If someone needs v3 he is free to enhance the code when it is released.