unum type I number system implementation

[Ravenwater]

Variable precision unum Type 1 are going to be useful to study numerical behavior of computation. The ubox and the variable precision will give us new information about how a computation evolves.

The ubox dynamics are going to be part of the valid number system as well, so when we have unum Type 1 and valid we can compare tough computational problems like root finding or discontinuous function evaluations.