Speedup the construction of the database. One of the issues is that models where inserted and committed one by one, which is very slow with SQLite. Now we rather insert all the models at once (for instance all the DL07 models) and commit only when this is done. Even on an SSD, the total run time of python setup.py build goes from 5m20s to 2m42s. The speedup should be even more spectacular on a rotating hard drive.