the "If I had a hammer" patch.

Had to answer the question, did it in code.

Much more accurrate results for 5.1


ndb/tools/ndb_size.pl:
  Add experimental 5.1-dd support to ndb_size.pl
  Improve calculations with 5.1 and variable sized attributes.
  
  Now much more closely resembles reality.
ndb/tools/ndb_size.tmpl:
  Comment on 5.1-dd exp support.
  
  Display:
  - nr varsized attributes
  - actual row overhead depending on version
  - overhead for varsized attributes