Literalize terms before starting the simplify.
Literalize terms before starting the simplify.

Previous:
```python
>>> parse("~A*~(~A+~B)")
AND(NOT(Symbol('A')), NOT(OR(NOT(Symbol('A')), NOT(Symbol('B')))))
```
Now:
```python
>>> parse("~A*~(~A+~B)")
FALSE
```
Kronuz/boolean.py,pombredanne/boolean.py,bastikr/boolean.py