* Optimise usings
* Enable Firebird Embedded tests at Travis CI
* fix for FirebirdProcessor.CreateSequenceForIdentity attempting to
  create undo expression when FBOptions.UndoEnabled is false
* 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.
* try different process for handling merged multiple statements for
  insert / delete as the prior method worked find on my windows machine
  and failed at travis (ie, under Linux)
  - split insert & delete operations into their own sub-expressions
    just before processing them
  - no need to do this on update as the syntax doesn't allow chaining
    of updates
* alter update table test to change a changeable field instead of attempting to change the PK field