Replace the RoseLiteral structure with more program instructions; now,
instead of each literal ID leading to a RoseLiteral, it simply has a
program to run (and a delay rebuild program).
This commit also makes some other improvements:
* CHECK_STATE instruction, for use instead of a sparse iterator over a
single element.
* Elide some checks (CHECK_LIT_EARLY, ANCHORED_DELAY, etc) when not
needed.
* Flatten PUSH_DELAYED behaviour to one instruction per delayed
literal, rather than the mask/index-list approach used before.
* Simple program cache at compile time for deduplication.
- cleanups
- add sparse iter instructions
- merge "root" and "sparse iter" programs together
- move program execution to new file program_runtime.h
- simplify EOD execution
- Use program for EOD sparse iterator
- Use program for literal sparse iterator
- Eliminate RoseRole, RosePred, RoseVertexProps::role
- Small performance optimizations
