Hi,

Attached is the patch that introduces telnet service which can accept 
and execute CLI commands from the remote user.
It is controlled by two additional MI commands: "-start-telnet-service 
[port]" and "-stop-telnet-service".

After the service is started, user can connect to the gdb via telnet and 
execute CLI commands in parallel with existing MI interface. Thereby it 
is something like a "backdoor" to the gdb.

The patch still needs some additional documentation/changelog entry, but 
the implementation is done in general and ready for the criticism. I'm 
also looking on posibility to add few automated testcases and integrate 
them in.

Current implementation assumes that the inferior is executed in async 
mode and requires "set target-async" to be set to "on".
Two additional options should also be turned on if remote user is going 
to issue interactive commands (like "commands", etc). They are "set 
confirm on" and "set interactive on" and can be set on-the-fly by the 
remote user.

The rest is quite straightforward. When the user connects over telnet, 
it receives gdb prompt and able to issue CLI commands and receive the 
result back.

Regards,
Grigory