Render string values insides double quotes.
Fix bitwise algorithm on compressed bitstreams.

The bitwise operation on compressed algorithms had a typo in which LHS and RHS
were reversed, which manifested as buggy asymmetric operations (NAND and NOR).
Remove redundant checks and conversions.
Change operator != for string bitmap indexes.

The semantics of :string != "foo" now mean "if there's any valid string that
isn't "X", I want it". By *valid*, we mean a string that is not optional and
has a set value.