Ensure proper exception is raised for invalid expression "a (and b)"
Ensure proper exception is raised for invalid expression "a (and b)"

 * "test_parse_invalid_nested_and_should_raise_a_proper_exception"
   was failing. This is now passing. A new check in parse() verifies
   that an opening parens "(" can only be preceded by a function or
   another opening parens, but by a symbol, or else.
   Raise a proper ParseError in these cases.
   
Signed-off-by: Philippe Ombredanne <ca95c4a6a4931f366cbdaf5878c5016609417d37@nexb.com>
pombredanne/boolean.py,bastikr/boolean.py