- Move TODO of <0 to !=-1 to boolean, as it's counter-productive otherwise.
- All a!=b except list!=list are equivalent to !(a==b).
- Change a>b to b<a to simplify cases to analize.
- Proper fall-through in some spots, or return in some others where it didn't apply.
- Simplify handling of a<-2147483648 as a&0, falling through, instead of coping with it ourselves.