[en] ssh_get_info + Telnet + SNMP

One of my customers never use SSH, but rather Telnet. This is frustrating as ssh_get_info cannot be used. So I patched ssh_get_info.nasl to support other protocols: Telnet, rexec, rsh & rlogin.
The code is now cleaner IMHO, and it should be easier to add more protocols, if this is really necessary.
We have to test all this to check that nothing is broken, do not expect to see this released too soon.

I also wrote a new snmp_get_info.nasl, but few systems give useful information through the (out of the box) SNMP agent: AIX, SuSE...
Maybe this script will never go into the official repository.