Bug fix: The integer? procedure no longer returns true for infinities.

A side effect of this bug was that the compile's common subexpression
elimination would crash when handling infinities, either written
literally or due to constant folding:

;  Compiling file: "./floenv.bin" => "./floenv.com"...
;The object +inf.0, passed as the first argument to flonum-normalize, is not the correct type.
