\x auto and EXPLAIN

Hi,

psql's "\x auto" is a nice feature, but it is made much less useful in
my opinion due to the expanded output format making query plans
unreadable (and query plans often end up using expanded display due to
their width). I think we should never use the expanded format for
EXPLAIN output in the "\x auto" mode, since even when the wrapped format
is used the query plans are very hard to read.

I see two ways to fix this.

1) Never use expanded display for the case where there is only one
column. There seems to me like there is little value in using expanded
display for when you only have one column, but I may be missing some use
case here.

2) Explicitly detect (for example based on the headers) that the result
is a query plan and if so disable expanded display.

I have attached a trivial patch for each solution.

Andreas