[gtp] Blank line except for Id

[Salvador Girbau]

Gents,
thanks for your work on the GTP. I have a [silly] question, IMO not clear in 
the protocol draft.

Blank lines are specified to be ignored. But what should an engine do with a 
line containing an Id, and nothing else?

If this counts too as a blank line, then the sender gets no acknowledge for 
some Id number.

If, on the other hand, a response
 =Id
should be issued, then this is inconsistent with the treatment of blank lines, 
which get no response.

Thanks,
Salvador