Partial revert of Mantis #2053:
http://scp.indiegames.us/mantis/view.php?id=2053
The patch was speculative and there was never a confirmed bug. By contrast, there are plenty of existing missions that use Unknown as a ship, wing, or jump node name and work just fine.
This introduces a new mechanism for handling bit flags. Instead of using an int (or two, or three) to write bits into, this uses the std::bitset in a wrapper class that accepts an enum class as input. This means that certain classes of errors we've had a few of in the engine, where a coder used the wrong set of flags or checked them against the wrong variable (SF_STEALTH vs SIF_STEALTH, for example) can now be detected at a compiler level rather than not at all.
Goober5000