Pretty Printer for KIF. Partially based on "pretty" instances in AS_CommonLogic. Note that the output does not perfectly match the input, as CommonLogic does not have the concept of "free variables" (as opposed to variables bound by a quantifier). Thus, any free variables are converted into constants and lose their ? prefix. When CommonLogic code is emitted as KIF, the comments in commented sentences and terms get lost, and modules are inlined.