pass query parameters through to metamodel syntax

[riastradh-probcomp]

Currently we do not distinguish

CREATE GENERATOR g FOR p USING m ("foo")

from

CREATE GENERATOR g FOR p USING m ('foo')

which is not at the moment blocking anything (hence the stall of #410), but which may be worth fixing soon. Furthermore, passing a verbatim string through, e.g. to provide the source code in

CREATE GENERATOR g FOR p USING cgpm (
    MODEL x GIVEN y USING venturescript (source = 'assume x = 42; ...')
)

as we kludgily do in

bayeslite/tests/test_vscgpm.py

Lines 166 to 179 in f3f27a5

	bdb.execute('''
	CREATE GENERATOR g0 FOR satellites USING cgpm (
	apogee NORMAL,
	LATENT kepler_cluster_id NUMERICAL,
	LATENT kepler_noise NUMERICAL,
	MODEL kepler_cluster_id, kepler_noise, period
	GIVEN apogee, perigee
	USING venturescript (source = "{}"),
	MODEL perigee GIVEN apogee USING linreg,
	MODEL class_of_orbit GIVEN apogee, period, perigee
	USING forest (k = 4),
	SUBSAMPLE 100,
	)
	'''.format(kepler_source))

with Python string formatting, is not easy to do reliably. That fragment just assumes no " appears in the VentureScript code, and abuses "..." quotation, which in SQL means names, with '...' meaning strings. No quotation should be necessary on the user's part -- it should be possible to do

bdb.execute('CREATE GENERATOR ... USING venturescript (source = ?) ...', (venturescript,))

and get the same intended effect reliably.