Remove the RoseEngine and stream state pointers frose RoseContext, as
they are also present in core_info.
Unify stream state handing in Rose to always use a char * (we were often
a u8 * for no particularly good reason) and tidy up.
- Use program for EOD sparse iterator
- Use program for literal sparse iterator
- Eliminate RoseRole, RosePred, RoseVertexProps::role
- Small performance optimizations