Don't double-quote identifiers in catalog queries.

Avoid double quoting the schema names when used in PostgreSQL catalog
queries, where the identifiers are used as literal values and need to be
single-quoted.

Fix #476, again.

src/pgsql/pgsql-schema.lisp

@@ -88,7 +88,7 @@
   "Return an expression suitable to be used as an :including parameter."
   (let ((schema (or (table-schema table)
                     (query-table-schema table))))
-    (list (cons (schema-name schema)
+    (list (cons (ensure-unquoted (schema-name schema))
                 (list
                  (format-table-name-as-including-exp table))))))
 

test/csv-hstore.load

@@ -1,6 +1,6 @@
 LOAD CSV
      FROM INLINE
-     INTO postgresql://dim@localhost/pgloader?"HS"
+     INTO postgresql://dim@localhost/pgloader?public."HS"
 
      WITH truncate,
           fields terminated by '\t',