New autocompletion feature

[Manuel S. <man...@gm...>]

Hi guys,

I often use commands like

plot "afile" w l <and many more options>, \
"anotherfile" w l <the same options>, \
...

So I implemented an auto completion feature for this, so you can use it 
like this:

plot "" <all your options>
       ^ place cursor here and press <tab>
result:
plot "file1" <all your options>,
  "file2" <all your options>,
  "file3" <all your options>

There is an minimal example application attached to this email but in 
this preprocessor command mix I cannot figure out where to place the 
rl_bind_key command in the gnuplot source code.

It would be great if you could tell me where to place this command so I 
can create a patch for this feature.

Please note that its feature should not remove the current <tab> feature 
and will via Alt+C or something.

Cheers,
Manuel