Revert "Add signed modulus"
Revert "Add signed modulus"

This reverts commits 5fa624d27e4e6ae3b9d268b02ce79b712598caff and
81cc1d5632415f2b4e661f754b324a9b66875198.

urbit/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,ohAitch/arvo,urbit/urbit,urbit/urbit,jfranklin9000/urbit,solri/arvo,jfranklin9000/urbit,ngzax/urbit,jfranklin9000/urbit,joemfb/arvo,ohAitch/arvo,Fang-/arvo,eglaysher/arvo,urbit/urbit,jfranklin9000/urbit,jfranklin9000/urbit,ngzax/urbit,ngzax/urbit,cgyarvin/arvo,urbit/urbit,joemfb/arvo,cgyarvin/arvo,jfranklin9000/urbit,belisarius222/arvo,belisarius222/arvo,ngzax/urbit,jfranklin9000/urbit,ngzax/urbit