Changed the parallelization of populate_gmf_agg
Change populate_gmf_agg to use the regular distribution mechanism
Added a needed UNIQUE constraint to the table gmf_agg
Improved a docstring
Changed the parallelization again to generate at most 16 tasks
Restored the GEOMETRY field in hzrdr.gmf
Restored the simplest distribution by point
Merge branch 'master' into parallelize-insert-into-gmf_agg
Fixed an error message
Merge pull request #1181 from gem/parallelize-insert-into-gmf_agg

Parallelize the queries of kind "insert into gmf agg" by using the standard mechanism
Merged from master