Module traits

This module contains additional traits I thought may be useful for BigNum usage.

Traits

• Pred
  This trait gets the previous valid value of a type. Mainly for BigNum, since subbing one often doesn’t result in a changing value. This is provided for contexts where you need to decrease the value easily
• Succ
  This trait gets the very next valid value of a type. Mainly for BigNum, since adding one often doesn’t result in a changing value. This is provided for contexts where you need to increase the value easily