CR: enable "scrutiny" be default

[felix winkelmann]

Flow- and type-analysis only enabled with the -scrutinize or -specialize options, or when an optimization-level > 2 is selected. Since the type-analysis can catch many errors, sjamaan suggested to enable scrutiny by default (note that this doesn't automatically imply specialization, i.e. optimizations based on the analysis).

To avoid incorrect warnings in code that redefines standard bindings, scrutiny should be disabled when the -no-usual-integrations option (implied by optimization level 0) is given.

[felix winkelmann]

Poll(Enable scrutiny by default?; Yes; No)?

[johnwcowan]

Replying to felix:

Poll(Enable scrutiny by default?; Yes; No)?

[felix winkelmann]

Accepted.