- Don't compile rules in parallel, but allow derivatives to be computed in parallel.
- Found a bug in the CharSet.difference function; it's not fixed yet, but now there's an assertion so we can detect when the bug occurs.
- Added (temporarily) a debug statement to notify when the wildcard pattern won't be matched.
- Fixed (seemingly) the bug in the CharSet.difference function.
- Added an assertion to check the output of the CharSet.union function, and it seems the same case that exposed the bug in CharSet.difference also found a bug in CharSet.union.