Added support for star query joins (important for data warehousing applications)
     -look at star_schema_queries.zip
   Support for multitable joins.
   Tested on a 1TB database (Star Schema Benchmark).
   Fixed a problem with grouping of datasets that do not fit GPU.
Changes to sql file definitions.
change.log
Defined string lengths from 1 to 20
Merge pull request #3 from antonmks/master

pull