docs and comments in make_query
allow order_by="length"; should add "file_order"
add FeatureDB.merge()
add children_bp method (useful for exonic bp)
separate dialect inference into one section
nicer verbose handling
docs & pep8
in create_db(), only use iterator._iter if using a consumable iterator
__getitem__ can take a Feature (for some reason this wasn't implemented yet..?)
parser_test fixes
more tests for db.update() (esp. when iterating)
add "from-prev-version", to use for updating refactor branch tests
some demo profiling scripts