Code generator *_get() ORM map

[ehuelsmann]

In LedgerSMB, we have a largish number of stored procedures which simply wrap

SELECT * FROM <table> WHERE <primary_key> = <the_object>

It seems like a nice extension of the ORM mapper to not have to write code like that.

[einhverfr]

We might indeed want to create a PGObject::Util module to be able to declaratively generate these.