RE: psql \df choose functions by their arguments

Hi

(sorry forget to cc the hacklist)

> Improve psql \df to choose functions by their arguments

I think this is useful.

I found some comments in the patch.

1.
> * Abbreviations of common types is permitted (because who really likes 
> to type out "character varying"?), so the above could also be written as:

some Abbreviations of common types are not added to the type_abbreviations[] Such as:

Int8                => bigint
Int2                => smallint
Int4 ,int           => integer
Float4              => real
Float8,float,double => double precision
(as same as array type)

Single array seems difficult to handle it, may be we can use double array or use a struct.

2.
And I think It's better to update '/?' info about '\df[+]' in function slashUsage(unsigned short int pager).

Best regards,
houzj