* bugfix: Firebird migrations involving table renames where the source
  table has more than one row of data fail because the Firebird engine
  doesn't like just getting a barrage of Insert statements separated by
  semi-colons like would be expected; instead, Firebird requires that
  these statements be wrapped in an execution block (see
  http://www.firebirdsql.org/refdocs/langrefupd20-execblock.html for
  more information).
  This fix wraps all insert, update and delete expression runs for data
  manipulation (single and multiple) in execution blocks.