Safety 0 is a bad idea

[slyrus]

Turning safety to 0 for so much of the code is a bad idea, and can mask real bugs. See next issue...

[varjagg]

It is, however other safety levels result in unacceptable performance penalties last time I tried. It's probably a combination of me being not smart enough to declare types properly and of SBCL unable to infer them.

It's a good idea to reduce them in scope to critical places, but is one of the things I haven't gotten around to yet.