Fix a number of show-stopping bugs in dbi_link.sql
Fix a number of show-stopping bugs in dbi_link.sql

- prepend_to_search_path() failed on PostgreSQL 8.4 because an SQL
  function returning VOID cannot end with an UPDATE
- Should be spi_exec_prepared and not spi_exec_query in subs quote_ident
  and quote_literal
- Respect remote_schema in shadow_trigger_func()
- Add escape character to LIKE wildcards in arguments for DBI functions
  table_info() and column_info()

davidfetter/DBI-Link