Revert "equip the elimination rules to work when goal is not truth (a bit ugly right now)"
Revert "equip the elimination rules to work when goal is not truth (a bit ugly right now)"

This reverts commit 894e458adc5600a18b3f025f1507a8611161abb0.

Close #128

ak3n/redprl,JonPRL/sml-red-jonprl,RedPRL/sml-redprl,ak3n/sml-red-jonprl,jozefg/sml-red-jonprl