Typically reduces storage overhead for snapshot maps by 60%.
The extensible format is a prerequisite for the next redesign steps:
Eliminate IR_FRAME and implement return-to-lower-frame.
Compile math.sinh(), math.cosh(), math.tanh() and math.random().
Compile various io.*() functions.
Drive the GC forward on string allocations in the parser.
Improve KNUM fuse vs. load heuristics.
Add abstract C call handling to IR.
Fix lua_tocfunction().
Fix cutoff register in JMP bytecode for some conditional expressions.
Fix PHI marking algorithm for references from variant slots.
