add flag to disable static contract optimization

[bennn]

Add a switch to turn off contract optimization.

(SCV-CR needs to disable the optimizations to do its analysis, and people like Shriram might want to show the full contracts for teaching)

This switch could piggyback on the PLT_TR_NO_OPTIMIZE / #:no-optimize flag, but then code that needs to disable those expression-level optimizations for safety is going to be slower than it needs to be at boundaries. So, it seems better to make a new switch.