Omit spurious T_SEMI.
Rename bayeslite.py to core.py to avoid module/package conflicts.
First loadable draft of BQL parser.

Doubtless won't successfully parse anything yet.
Add a parser test and make it pass.
Expand parser test_empty.
Add trivial select test and make it pass.
Fix parsing `<exp> AS <col>' in select column.
Scan `*' token and test it.
Scan `.' token and test it.
Scan `,' token and test it.
Implement `select ... from tab as t'.
Simplify some tests to reduce verbiage.
Pass arguments to check.sh through to py.test.
Add trivial SELECT WHERE test.
Add trivial GROUP BY tests.
Add trivial SELECT LIMIT tests.
Scan `='.
Add trivial BQL function parse tests.