Convert Postgres arrays to Perl arrays on PL/perl input arguments
 
More generally, arrays are turned in Perl array references, and row and
composite types are turned into Perl hash references.  This is done
recursively, in a way that's natural to every Perl programmer.
 
To avoid a backwards compatibility hit, the string representation of
each structure is also available if the function requests it.
 
Authors: Alexey Klyukin and Alex Hunsaker.
Some code cleanups by me.