Spruced up the typechecking test.

+ Verifying Expected Failures
+ pass  1/2 expressions from psp-show should typecheck
+ pass  12/24 expressions from psp-by-equals should typecheck
+ pass  0/24 expressions from psp-by-ref should typecheck
+ pass  14/24 expressions from psp-straight should typecheck
+ pass  24/24 expressions from scala-library should typecheck