ver 1.20g(1.21's beta) firmware

1. Fixed not open problem of "network" tap in the browser of Firefox, Crom, Opera. 
2. Made up a weak points of the MTU value and Mac cloning function.
3. Made up a weak points of the problem of "renew IP address"
4. Added "Mediatomb" and for details, please check to the web management page : APPS & SERVICES-Services-service control. 
5. In PPPoA, one more usb modem supports. 
- Model name: Thomson SpeedTouch 330 (link: <http://seekbroadband.com/hardware/USB-Modems/Thomson-SpeedTouch-330-USB-ADSL-Modem>).
- Must need upgrade "HDD Image(ver 1.13). 
6. Made up a problem of firmware upgrding failure(once in a while) in PPPoA, PPPoE and PPTP. 
7. Help message added to the following : WAN, OPENVPN, BITTORENT, MEDIATOMB. 
8. Fixed long file name of Bittorent to be downloaded.  
9. Fixed a problem of not-open the GUI window(once in a while) after finishing firmware upgrading. 
10. Miscellaneous bugs fix.