Don't call to crosscat for zero-iteration analysis.

This change had been sitting in my working tree uncommitted for a
while, and turned out to be necessary to make the tests pass.  Oops.
So I am reordering it to before I introduced the tests using `git
rebase', with apologies for the forced-update.
Add some automatic smoke tests.
Add unconstrained simulate smoke test.
Fix order of substitands in bayesdb_cell_value SQL query.
Add constrained simulate smoke test.
Capitalize NaN consistently.
Fix categorical/categorical correlation indexing.

Not sure it computes the right thing yet but now it doesn't crash.
Add column correlation smoke test.
Add copyright notice to test_smoke.py.
Explain why test_t1_simulate looks funny.
Add smoke tests for some more column functions.

- typicality
- dependence probability
- mutual information
Add column value probability smoke test.
Fix edge cases of short arrays unique_indices.
Explicitly skip t0 in test_twocolumn.
Smoke tests for row functions.
Test some screw cases of bql schemas.
Fix multi-key test to tickle the right error.
Test automatic key selection.
Add CSV import tests.
Fix arity of row_column_predictive_probability.